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28f540f4 | 1 | @node Pattern Matching, I/O Overview, Searching and Sorting, Top |
7a68c94a | 2 | @c %MENU% Matching shell ``globs'' and regular expressions |
28f540f4 RM |
3 | @chapter Pattern Matching |
4 | ||
1f77f049 | 5 | @Theglibc{} provides pattern matching facilities for two kinds of |
28f540f4 RM |
6 | patterns: regular expressions and file-name wildcards. The library also |
7 | provides a facility for expanding variable and command references and | |
8 | parsing text into words in the way the shell does. | |
9 | ||
10 | @menu | |
11 | * Wildcard Matching:: Matching a wildcard pattern against a single string. | |
12 | * Globbing:: Finding the files that match a wildcard pattern. | |
13 | * Regular Expressions:: Matching regular expressions against strings. | |
14 | * Word Expansion:: Expanding shell variables, nested commands, | |
15 | arithmetic, and wildcards. | |
16 | This is what the shell does with shell commands. | |
17 | @end menu | |
18 | ||
19 | @node Wildcard Matching | |
20 | @section Wildcard Matching | |
21 | ||
22 | @pindex fnmatch.h | |
23 | This section describes how to match a wildcard pattern against a | |
24 | particular string. The result is a yes or no answer: does the | |
25 | string fit the pattern or not. The symbols described here are all | |
26 | declared in @file{fnmatch.h}. | |
27 | ||
28 | @comment fnmatch.h | |
29 | @comment POSIX.2 | |
30 | @deftypefun int fnmatch (const char *@var{pattern}, const char *@var{string}, int @var{flags}) | |
03483ada AO |
31 | @safety{@prelim{}@mtsafe{@mtsenv{} @mtslocale{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}} |
32 | @c fnmatch @mtsenv @mtslocale @ascuheap @acsmem | |
33 | @c strnlen dup ok | |
34 | @c mbsrtowcs | |
35 | @c memset dup ok | |
36 | @c malloc dup @ascuheap @acsmem | |
37 | @c mbsinit dup ok | |
38 | @c free dup @ascuheap @acsmem | |
39 | @c FCT = internal_fnwmatch @mtsenv @mtslocale @ascuheap @acsmem | |
40 | @c FOLD @mtslocale | |
41 | @c towlower @mtslocale | |
42 | @c EXT @mtsenv @mtslocale @ascuheap @acsmem | |
43 | @c STRLEN = wcslen dup ok | |
44 | @c getenv @mtsenv | |
45 | @c malloc dup @ascuheap @acsmem | |
46 | @c MEMPCPY = wmempcpy dup ok | |
47 | @c FCT dup @mtsenv @mtslocale @ascuheap @acsmem | |
48 | @c STRCAT = wcscat dup ok | |
49 | @c free dup @ascuheap @acsmem | |
50 | @c END @mtsenv | |
51 | @c getenv @mtsenv | |
52 | @c MEMCHR = wmemchr dup ok | |
53 | @c getenv @mtsenv | |
54 | @c IS_CHAR_CLASS = is_char_class @mtslocale | |
55 | @c wctype @mtslocale | |
56 | @c BTOWC ok | |
57 | @c ISWCTYPE ok | |
58 | @c auto findidx dup ok | |
59 | @c elem_hash dup ok | |
60 | @c memcmp dup ok | |
61 | @c collseq_table_lookup dup ok | |
62 | @c NO_LEADING_PERIOD ok | |
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63 | This function tests whether the string @var{string} matches the pattern |
64 | @var{pattern}. It returns @code{0} if they do match; otherwise, it | |
65 | returns the nonzero value @code{FNM_NOMATCH}. The arguments | |
66 | @var{pattern} and @var{string} are both strings. | |
67 | ||
68 | The argument @var{flags} is a combination of flag bits that alter the | |
69 | details of matching. See below for a list of the defined flags. | |
70 | ||
ca42d35e OB |
71 | In @theglibc{}, @code{fnmatch} might sometimes report ``errors'' by |
72 | returning nonzero values that are not equal to @code{FNM_NOMATCH}. | |
28f540f4 RM |
73 | @end deftypefun |
74 | ||
75 | These are the available flags for the @var{flags} argument: | |
76 | ||
77 | @table @code | |
78 | @comment fnmatch.h | |
79 | @comment GNU | |
80 | @item FNM_FILE_NAME | |
81 | Treat the @samp{/} character specially, for matching file names. If | |
82 | this flag is set, wildcard constructs in @var{pattern} cannot match | |
83 | @samp{/} in @var{string}. Thus, the only way to match @samp{/} is with | |
84 | an explicit @samp{/} in @var{pattern}. | |
85 | ||
86 | @comment fnmatch.h | |
87 | @comment POSIX.2 | |
88 | @item FNM_PATHNAME | |
89 | This is an alias for @code{FNM_FILE_NAME}; it comes from POSIX.2. We | |
90 | don't recommend this name because we don't use the term ``pathname'' for | |
91 | file names. | |
92 | ||
93 | @comment fnmatch.h | |
94 | @comment POSIX.2 | |
95 | @item FNM_PERIOD | |
96 | Treat the @samp{.} character specially if it appears at the beginning of | |
97 | @var{string}. If this flag is set, wildcard constructs in @var{pattern} | |
98 | cannot match @samp{.} as the first character of @var{string}. | |
99 | ||
100 | If you set both @code{FNM_PERIOD} and @code{FNM_FILE_NAME}, then the | |
101 | special treatment applies to @samp{.} following @samp{/} as well as to | |
102 | @samp{.} at the beginning of @var{string}. (The shell uses the | |
6952e59e | 103 | @code{FNM_PERIOD} and @code{FNM_FILE_NAME} flags together for matching |
28f540f4 RM |
104 | file names.) |
105 | ||
106 | @comment fnmatch.h | |
107 | @comment POSIX.2 | |
108 | @item FNM_NOESCAPE | |
109 | Don't treat the @samp{\} character specially in patterns. Normally, | |
110 | @samp{\} quotes the following character, turning off its special meaning | |
111 | (if any) so that it matches only itself. When quoting is enabled, the | |
112 | pattern @samp{\?} matches only the string @samp{?}, because the question | |
113 | mark in the pattern acts like an ordinary character. | |
114 | ||
115 | If you use @code{FNM_NOESCAPE}, then @samp{\} is an ordinary character. | |
116 | ||
117 | @comment fnmatch.h | |
118 | @comment GNU | |
119 | @item FNM_LEADING_DIR | |
120 | Ignore a trailing sequence of characters starting with a @samp{/} in | |
121 | @var{string}; that is to say, test whether @var{string} starts with a | |
122 | directory name that @var{pattern} matches. | |
123 | ||
124 | If this flag is set, either @samp{foo*} or @samp{foobar} as a pattern | |
125 | would match the string @samp{foobar/frobozz}. | |
126 | ||
127 | @comment fnmatch.h | |
128 | @comment GNU | |
129 | @item FNM_CASEFOLD | |
130 | Ignore case in comparing @var{string} to @var{pattern}. | |
821a6bb4 UD |
131 | |
132 | @comment fnmatch.h | |
133 | @comment GNU | |
134 | @item FNM_EXTMATCH | |
135 | @cindex Korn Shell | |
136 | @pindex ksh | |
137 | Recognize beside the normal patterns also the extended patterns | |
138 | introduced in @file{ksh}. The patterns are written in the form | |
139 | explained in the following table where @var{pattern-list} is a @code{|} | |
140 | separated list of patterns. | |
141 | ||
142 | @table @code | |
143 | @item ?(@var{pattern-list}) | |
0bc93a2f | 144 | The pattern matches if zero or one occurrences of any of the patterns |
821a6bb4 UD |
145 | in the @var{pattern-list} allow matching the input string. |
146 | ||
147 | @item *(@var{pattern-list}) | |
0bc93a2f | 148 | The pattern matches if zero or more occurrences of any of the patterns |
821a6bb4 UD |
149 | in the @var{pattern-list} allow matching the input string. |
150 | ||
151 | @item +(@var{pattern-list}) | |
0bc93a2f | 152 | The pattern matches if one or more occurrences of any of the patterns |
821a6bb4 UD |
153 | in the @var{pattern-list} allow matching the input string. |
154 | ||
155 | @item @@(@var{pattern-list}) | |
0bc93a2f | 156 | The pattern matches if exactly one occurrence of any of the patterns in |
821a6bb4 UD |
157 | the @var{pattern-list} allows matching the input string. |
158 | ||
159 | @item !(@var{pattern-list}) | |
160 | The pattern matches if the input string cannot be matched with any of | |
161 | the patterns in the @var{pattern-list}. | |
162 | @end table | |
28f540f4 RM |
163 | @end table |
164 | ||
165 | @node Globbing | |
166 | @section Globbing | |
167 | ||
168 | @cindex globbing | |
169 | The archetypal use of wildcards is for matching against the files in a | |
170 | directory, and making a list of all the matches. This is called | |
171 | @dfn{globbing}. | |
172 | ||
173 | You could do this using @code{fnmatch}, by reading the directory entries | |
174 | one by one and testing each one with @code{fnmatch}. But that would be | |
175 | slow (and complex, since you would have to handle subdirectories by | |
176 | hand). | |
177 | ||
178 | The library provides a function @code{glob} to make this particular use | |
179 | of wildcards convenient. @code{glob} and the other symbols in this | |
180 | section are declared in @file{glob.h}. | |
181 | ||
182 | @menu | |
714a562f UD |
183 | * Calling Glob:: Basic use of @code{glob}. |
184 | * Flags for Globbing:: Flags that enable various options in @code{glob}. | |
185 | * More Flags for Globbing:: GNU specific extensions to @code{glob}. | |
28f540f4 RM |
186 | @end menu |
187 | ||
188 | @node Calling Glob | |
189 | @subsection Calling @code{glob} | |
190 | ||
191 | The result of globbing is a vector of file names (strings). To return | |
192 | this vector, @code{glob} uses a special data type, @code{glob_t}, which | |
193 | is a structure. You pass @code{glob} the address of the structure, and | |
194 | it fills in the structure's fields to tell you about the results. | |
195 | ||
196 | @comment glob.h | |
197 | @comment POSIX.2 | |
198 | @deftp {Data Type} glob_t | |
199 | This data type holds a pointer to a word vector. More precisely, it | |
714a562f UD |
200 | records both the address of the word vector and its size. The GNU |
201 | implementation contains some more fields which are non-standard | |
202 | extensions. | |
28f540f4 RM |
203 | |
204 | @table @code | |
205 | @item gl_pathc | |
460adbb8 UD |
206 | The number of elements in the vector, excluding the initial null entries |
207 | if the GLOB_DOOFFS flag is used (see gl_offs below). | |
28f540f4 RM |
208 | |
209 | @item gl_pathv | |
210 | The address of the vector. This field has type @w{@code{char **}}. | |
211 | ||
212 | @item gl_offs | |
213 | The offset of the first real element of the vector, from its nominal | |
214 | address in the @code{gl_pathv} field. Unlike the other fields, this | |
215 | is always an input to @code{glob}, rather than an output from it. | |
216 | ||
217 | If you use a nonzero offset, then that many elements at the beginning of | |
218 | the vector are left empty. (The @code{glob} function fills them with | |
219 | null pointers.) | |
220 | ||
221 | The @code{gl_offs} field is meaningful only if you use the | |
222 | @code{GLOB_DOOFFS} flag. Otherwise, the offset is always zero | |
223 | regardless of what is in this field, and the first real element comes at | |
224 | the beginning of the vector. | |
714a562f UD |
225 | |
226 | @item gl_closedir | |
227 | The address of an alternative implementation of the @code{closedir} | |
228 | function. It is used if the @code{GLOB_ALTDIRFUNC} bit is set in | |
229 | the flag parameter. The type of this field is | |
230 | @w{@code{void (*) (void *)}}. | |
231 | ||
232 | This is a GNU extension. | |
233 | ||
234 | @item gl_readdir | |
235 | The address of an alternative implementation of the @code{readdir} | |
236 | function used to read the contents of a directory. It is used if the | |
237 | @code{GLOB_ALTDIRFUNC} bit is set in the flag parameter. The type of | |
238 | this field is @w{@code{struct dirent *(*) (void *)}}. | |
239 | ||
240 | This is a GNU extension. | |
241 | ||
242 | @item gl_opendir | |
243 | The address of an alternative implementation of the @code{opendir} | |
244 | function. It is used if the @code{GLOB_ALTDIRFUNC} bit is set in | |
245 | the flag parameter. The type of this field is | |
246 | @w{@code{void *(*) (const char *)}}. | |
247 | ||
248 | This is a GNU extension. | |
249 | ||
250 | @item gl_stat | |
251 | The address of an alternative implementation of the @code{stat} function | |
252 | to get information about an object in the filesystem. It is used if the | |
253 | @code{GLOB_ALTDIRFUNC} bit is set in the flag parameter. The type of | |
254 | this field is @w{@code{int (*) (const char *, struct stat *)}}. | |
255 | ||
256 | This is a GNU extension. | |
257 | ||
258 | @item gl_lstat | |
259 | The address of an alternative implementation of the @code{lstat} | |
260 | function to get information about an object in the filesystems, not | |
261 | following symbolic links. It is used if the @code{GLOB_ALTDIRFUNC} bit | |
838e5ffe UD |
262 | is set in the flag parameter. The type of this field is @code{@w{int |
263 | (*) (const char *,} @w{struct stat *)}}. | |
714a562f | 264 | |
0428cec9 MF |
265 | This is a GNU extension. |
266 | ||
267 | @item gl_flags | |
268 | The flags used when @code{glob} was called. In addition, @code{GLOB_MAGCHAR} | |
269 | might be set. See @ref{Flags for Globbing} for more details. | |
270 | ||
714a562f | 271 | This is a GNU extension. |
28f540f4 RM |
272 | @end table |
273 | @end deftp | |
274 | ||
0fc95b82 UD |
275 | For use in the @code{glob64} function @file{glob.h} contains another |
276 | definition for a very similar type. @code{glob64_t} differs from | |
277 | @code{glob_t} only in the types of the members @code{gl_readdir}, | |
278 | @code{gl_stat}, and @code{gl_lstat}. | |
279 | ||
280 | @comment glob.h | |
281 | @comment GNU | |
282 | @deftp {Data Type} glob64_t | |
283 | This data type holds a pointer to a word vector. More precisely, it | |
284 | records both the address of the word vector and its size. The GNU | |
285 | implementation contains some more fields which are non-standard | |
286 | extensions. | |
287 | ||
288 | @table @code | |
289 | @item gl_pathc | |
290 | The number of elements in the vector, excluding the initial null entries | |
291 | if the GLOB_DOOFFS flag is used (see gl_offs below). | |
292 | ||
293 | @item gl_pathv | |
294 | The address of the vector. This field has type @w{@code{char **}}. | |
295 | ||
296 | @item gl_offs | |
297 | The offset of the first real element of the vector, from its nominal | |
298 | address in the @code{gl_pathv} field. Unlike the other fields, this | |
299 | is always an input to @code{glob}, rather than an output from it. | |
300 | ||
301 | If you use a nonzero offset, then that many elements at the beginning of | |
302 | the vector are left empty. (The @code{glob} function fills them with | |
303 | null pointers.) | |
304 | ||
305 | The @code{gl_offs} field is meaningful only if you use the | |
306 | @code{GLOB_DOOFFS} flag. Otherwise, the offset is always zero | |
307 | regardless of what is in this field, and the first real element comes at | |
308 | the beginning of the vector. | |
309 | ||
310 | @item gl_closedir | |
311 | The address of an alternative implementation of the @code{closedir} | |
312 | function. It is used if the @code{GLOB_ALTDIRFUNC} bit is set in | |
313 | the flag parameter. The type of this field is | |
314 | @w{@code{void (*) (void *)}}. | |
315 | ||
316 | This is a GNU extension. | |
317 | ||
318 | @item gl_readdir | |
319 | The address of an alternative implementation of the @code{readdir64} | |
320 | function used to read the contents of a directory. It is used if the | |
321 | @code{GLOB_ALTDIRFUNC} bit is set in the flag parameter. The type of | |
322 | this field is @w{@code{struct dirent64 *(*) (void *)}}. | |
323 | ||
324 | This is a GNU extension. | |
325 | ||
326 | @item gl_opendir | |
327 | The address of an alternative implementation of the @code{opendir} | |
328 | function. It is used if the @code{GLOB_ALTDIRFUNC} bit is set in | |
329 | the flag parameter. The type of this field is | |
330 | @w{@code{void *(*) (const char *)}}. | |
331 | ||
332 | This is a GNU extension. | |
333 | ||
334 | @item gl_stat | |
335 | The address of an alternative implementation of the @code{stat64} function | |
336 | to get information about an object in the filesystem. It is used if the | |
337 | @code{GLOB_ALTDIRFUNC} bit is set in the flag parameter. The type of | |
338 | this field is @w{@code{int (*) (const char *, struct stat64 *)}}. | |
339 | ||
340 | This is a GNU extension. | |
341 | ||
342 | @item gl_lstat | |
343 | The address of an alternative implementation of the @code{lstat64} | |
344 | function to get information about an object in the filesystems, not | |
345 | following symbolic links. It is used if the @code{GLOB_ALTDIRFUNC} bit | |
346 | is set in the flag parameter. The type of this field is @code{@w{int | |
347 | (*) (const char *,} @w{struct stat64 *)}}. | |
348 | ||
0428cec9 MF |
349 | This is a GNU extension. |
350 | ||
351 | @item gl_flags | |
352 | The flags used when @code{glob} was called. In addition, @code{GLOB_MAGCHAR} | |
353 | might be set. See @ref{Flags for Globbing} for more details. | |
354 | ||
0fc95b82 UD |
355 | This is a GNU extension. |
356 | @end table | |
357 | @end deftp | |
358 | ||
28f540f4 RM |
359 | @comment glob.h |
360 | @comment POSIX.2 | |
361 | @deftypefun int glob (const char *@var{pattern}, int @var{flags}, int (*@var{errfunc}) (const char *@var{filename}, int @var{error-code}), glob_t *@var{vector-ptr}) | |
03483ada AO |
362 | @safety{@prelim{}@mtunsafe{@mtasurace{:utent} @mtsenv{} @mtascusig{:ALRM} @mtascutimer{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}} |
363 | @c glob @mtasurace:utent @mtsenv @mtascusig:ALRM @mtascutimer @mtslocale @ascudlopen @ascuplugin @asucorrupt @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
364 | @c strlen dup ok | |
365 | @c strchr dup ok | |
366 | @c malloc dup @ascuheap @acsmem | |
367 | @c mempcpy dup ok | |
368 | @c next_brace_sub ok | |
369 | @c free dup @ascuheap @acsmem | |
370 | @c globfree dup @asucorrupt @ascuheap @acucorrupt @acsmem | |
371 | @c glob_pattern_p ok | |
372 | @c glob_pattern_type dup ok | |
373 | @c getenv dup @mtsenv | |
374 | @c GET_LOGIN_NAME_MAX ok | |
375 | @c getlogin_r dup @mtasurace:utent @mtascusig:ALRM @mtascutimer @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
376 | @c GETPW_R_SIZE_MAX ok | |
377 | @c getpwnam_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
378 | @c realloc dup @ascuheap @acsmem | |
379 | @c memcpy dup ok | |
380 | @c memchr dup ok | |
381 | @c *pglob->gl_stat user-supplied | |
382 | @c stat64 dup ok | |
383 | @c S_ISDIR dup ok | |
384 | @c strdup dup @ascuheap @acsmem | |
385 | @c glob_pattern_type ok | |
386 | @c glob_in_dir @mtsenv @mtslocale @asucorrupt @ascuheap @acucorrupt @acsfd @acsmem | |
387 | @c strlen dup ok | |
388 | @c glob_pattern_type dup ok | |
389 | @c malloc dup @ascuheap @acsmem | |
390 | @c mempcpy dup ok | |
391 | @c *pglob->gl_stat user-supplied | |
392 | @c stat64 dup ok | |
393 | @c free dup @ascuheap @acsmem | |
394 | @c *pglob->gl_opendir user-supplied | |
395 | @c opendir dup @ascuheap @acsmem @acsfd | |
396 | @c dirfd dup ok | |
397 | @c *pglob->gl_readdir user-supplied | |
398 | @c CONVERT_DIRENT_DIRENT64 ok | |
399 | @c readdir64 ok [protected by exclusive use of the stream] | |
400 | @c REAL_DIR_ENTRY ok | |
401 | @c DIRENT_MIGHT_BE_DIR ok | |
402 | @c fnmatch dup @mtsenv @mtslocale @ascuheap @acsmem | |
403 | @c DIRENT_MIGHT_BE_SYMLINK ok | |
404 | @c link_exists_p ok | |
405 | @c link_exists2_p ok | |
406 | @c strlen dup ok | |
407 | @c mempcpy dup ok | |
408 | @c *pglob->gl_stat user-supplied | |
409 | @c fxstatat64 dup ok | |
410 | @c realloc dup @ascuheap @acsmem | |
411 | @c pglob->gl_closedir user-supplied | |
412 | @c closedir @ascuheap @acsmem @acsfd | |
413 | @c prefix_array dup @asucorrupt @ascuheap @acucorrupt @acsmem | |
414 | @c strlen dup ok | |
415 | @c malloc dup @ascuheap @acsmem | |
416 | @c free dup @ascuheap @acsmem | |
417 | @c mempcpy dup ok | |
418 | @c strcpy dup ok | |
28f540f4 RM |
419 | The function @code{glob} does globbing using the pattern @var{pattern} |
420 | in the current directory. It puts the result in a newly allocated | |
421 | vector, and stores the size and address of this vector into | |
422 | @code{*@var{vector-ptr}}. The argument @var{flags} is a combination of | |
423 | bit flags; see @ref{Flags for Globbing}, for details of the flags. | |
424 | ||
425 | The result of globbing is a sequence of file names. The function | |
426 | @code{glob} allocates a string for each resulting word, then | |
427 | allocates a vector of type @code{char **} to store the addresses of | |
428 | these strings. The last element of the vector is a null pointer. | |
429 | This vector is called the @dfn{word vector}. | |
430 | ||
431 | To return this vector, @code{glob} stores both its address and its | |
432 | length (number of elements, not counting the terminating null pointer) | |
433 | into @code{*@var{vector-ptr}}. | |
434 | ||
6d52618b | 435 | Normally, @code{glob} sorts the file names alphabetically before |
28f540f4 RM |
436 | returning them. You can turn this off with the flag @code{GLOB_NOSORT} |
437 | if you want to get the information as fast as possible. Usually it's | |
438 | a good idea to let @code{glob} sort them---if you process the files in | |
439 | alphabetical order, the users will have a feel for the rate of progress | |
440 | that your application is making. | |
441 | ||
442 | If @code{glob} succeeds, it returns 0. Otherwise, it returns one | |
443 | of these error codes: | |
444 | ||
0fc95b82 | 445 | @vtable @code |
28f540f4 RM |
446 | @comment glob.h |
447 | @comment POSIX.2 | |
448 | @item GLOB_ABORTED | |
449 | There was an error opening a directory, and you used the flag | |
450 | @code{GLOB_ERR} or your specified @var{errfunc} returned a nonzero | |
451 | value. | |
452 | @iftex | |
453 | See below | |
454 | @end iftex | |
455 | @ifinfo | |
456 | @xref{Flags for Globbing}, | |
457 | @end ifinfo | |
458 | for an explanation of the @code{GLOB_ERR} flag and @var{errfunc}. | |
459 | ||
460 | @comment glob.h | |
461 | @comment POSIX.2 | |
462 | @item GLOB_NOMATCH | |
463 | The pattern didn't match any existing files. If you use the | |
464 | @code{GLOB_NOCHECK} flag, then you never get this error code, because | |
465 | that flag tells @code{glob} to @emph{pretend} that the pattern matched | |
466 | at least one file. | |
467 | ||
468 | @comment glob.h | |
469 | @comment POSIX.2 | |
470 | @item GLOB_NOSPACE | |
471 | It was impossible to allocate memory to hold the result. | |
0fc95b82 | 472 | @end vtable |
28f540f4 RM |
473 | |
474 | In the event of an error, @code{glob} stores information in | |
475 | @code{*@var{vector-ptr}} about all the matches it has found so far. | |
0fc95b82 | 476 | |
0bc93a2f | 477 | It is important to notice that the @code{glob} function will not fail if |
0fc95b82 UD |
478 | it encounters directories or files which cannot be handled without the |
479 | LFS interfaces. The implementation of @code{glob} is supposed to use | |
480 | these functions internally. This at least is the assumptions made by | |
481 | the Unix standard. The GNU extension of allowing the user to provide | |
482 | own directory handling and @code{stat} functions complicates things a | |
483 | bit. If these callback functions are used and a large file or directory | |
484 | is encountered @code{glob} @emph{can} fail. | |
485 | @end deftypefun | |
486 | ||
487 | @comment glob.h | |
488 | @comment GNU | |
489 | @deftypefun int glob64 (const char *@var{pattern}, int @var{flags}, int (*@var{errfunc}) (const char *@var{filename}, int @var{error-code}), glob64_t *@var{vector-ptr}) | |
03483ada AO |
490 | @safety{@prelim{}@mtunsafe{@mtasurace{:utent} @mtsenv{} @mtascusig{:ALRM} @mtascutimer{} @mtslocale{}}@asunsafe{@ascudlopen{} @asucorrupt{} @ascuheap{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}} |
491 | @c Same code as glob, but with glob64_t #defined as glob_t. | |
0fc95b82 UD |
492 | The @code{glob64} function was added as part of the Large File Summit |
493 | extensions but is not part of the original LFS proposal. The reason for | |
494 | this is simple: it is not necessary. The necessity for a @code{glob64} | |
495 | function is added by the extensions of the GNU @code{glob} | |
496 | implementation which allows the user to provide own directory handling | |
497 | and @code{stat} functions. The @code{readdir} and @code{stat} functions | |
498 | do depend on the choice of @code{_FILE_OFFSET_BITS} since the definition | |
499 | of the types @code{struct dirent} and @code{struct stat} will change | |
500 | depending on the choice. | |
501 | ||
502 | Beside this difference the @code{glob64} works just like @code{glob} in | |
503 | all aspects. | |
504 | ||
505 | This function is a GNU extension. | |
28f540f4 RM |
506 | @end deftypefun |
507 | ||
508 | @node Flags for Globbing | |
509 | @subsection Flags for Globbing | |
510 | ||
e557e9e5 | 511 | This section describes the standard flags that you can specify in the |
28f540f4 RM |
512 | @var{flags} argument to @code{glob}. Choose the flags you want, |
513 | and combine them with the C bitwise OR operator @code{|}. | |
514 | ||
e557e9e5 MF |
515 | Note that there are @ref{More Flags for Globbing} available as GNU extensions. |
516 | ||
0fc95b82 | 517 | @vtable @code |
28f540f4 RM |
518 | @comment glob.h |
519 | @comment POSIX.2 | |
520 | @item GLOB_APPEND | |
521 | Append the words from this expansion to the vector of words produced by | |
522 | previous calls to @code{glob}. This way you can effectively expand | |
523 | several words as if they were concatenated with spaces between them. | |
524 | ||
525 | In order for appending to work, you must not modify the contents of the | |
526 | word vector structure between calls to @code{glob}. And, if you set | |
527 | @code{GLOB_DOOFFS} in the first call to @code{glob}, you must also | |
528 | set it when you append to the results. | |
529 | ||
530 | Note that the pointer stored in @code{gl_pathv} may no longer be valid | |
531 | after you call @code{glob} the second time, because @code{glob} might | |
532 | have relocated the vector. So always fetch @code{gl_pathv} from the | |
533 | @code{glob_t} structure after each @code{glob} call; @strong{never} save | |
534 | the pointer across calls. | |
535 | ||
536 | @comment glob.h | |
537 | @comment POSIX.2 | |
538 | @item GLOB_DOOFFS | |
539 | Leave blank slots at the beginning of the vector of words. | |
540 | The @code{gl_offs} field says how many slots to leave. | |
541 | The blank slots contain null pointers. | |
542 | ||
543 | @comment glob.h | |
544 | @comment POSIX.2 | |
545 | @item GLOB_ERR | |
546 | Give up right away and report an error if there is any difficulty | |
547 | reading the directories that must be read in order to expand @var{pattern} | |
548 | fully. Such difficulties might include a directory in which you don't | |
549 | have the requisite access. Normally, @code{glob} tries its best to keep | |
550 | on going despite any errors, reading whatever directories it can. | |
551 | ||
552 | You can exercise even more control than this by specifying an | |
553 | error-handler function @var{errfunc} when you call @code{glob}. If | |
554 | @var{errfunc} is not a null pointer, then @code{glob} doesn't give up | |
555 | right away when it can't read a directory; instead, it calls | |
556 | @var{errfunc} with two arguments, like this: | |
557 | ||
558 | @smallexample | |
559 | (*@var{errfunc}) (@var{filename}, @var{error-code}) | |
560 | @end smallexample | |
561 | ||
562 | @noindent | |
563 | The argument @var{filename} is the name of the directory that | |
564 | @code{glob} couldn't open or couldn't read, and @var{error-code} is the | |
565 | @code{errno} value that was reported to @code{glob}. | |
566 | ||
567 | If the error handler function returns nonzero, then @code{glob} gives up | |
568 | right away. Otherwise, it continues. | |
569 | ||
570 | @comment glob.h | |
571 | @comment POSIX.2 | |
572 | @item GLOB_MARK | |
573 | If the pattern matches the name of a directory, append @samp{/} to the | |
574 | directory's name when returning it. | |
575 | ||
576 | @comment glob.h | |
577 | @comment POSIX.2 | |
578 | @item GLOB_NOCHECK | |
579 | If the pattern doesn't match any file names, return the pattern itself | |
580 | as if it were a file name that had been matched. (Normally, when the | |
581 | pattern doesn't match anything, @code{glob} returns that there were no | |
582 | matches.) | |
583 | ||
28f540f4 RM |
584 | @comment glob.h |
585 | @comment POSIX.2 | |
586 | @item GLOB_NOESCAPE | |
587 | Don't treat the @samp{\} character specially in patterns. Normally, | |
588 | @samp{\} quotes the following character, turning off its special meaning | |
589 | (if any) so that it matches only itself. When quoting is enabled, the | |
590 | pattern @samp{\?} matches only the string @samp{?}, because the question | |
591 | mark in the pattern acts like an ordinary character. | |
592 | ||
593 | If you use @code{GLOB_NOESCAPE}, then @samp{\} is an ordinary character. | |
594 | ||
595 | @code{glob} does its work by calling the function @code{fnmatch} | |
596 | repeatedly. It handles the flag @code{GLOB_NOESCAPE} by turning on the | |
597 | @code{FNM_NOESCAPE} flag in calls to @code{fnmatch}. | |
aba5e596 MF |
598 | |
599 | @comment glob.h | |
600 | @comment POSIX.2 | |
601 | @item GLOB_NOSORT | |
602 | Don't sort the file names; return them in no particular order. | |
603 | (In practice, the order will depend on the order of the entries in | |
604 | the directory.) The only reason @emph{not} to sort is to save time. | |
0fc95b82 | 605 | @end vtable |
28f540f4 | 606 | |
714a562f UD |
607 | @node More Flags for Globbing |
608 | @subsection More Flags for Globbing | |
609 | ||
f2ea0f5b | 610 | Beside the flags described in the last section, the GNU implementation of |
714a562f UD |
611 | @code{glob} allows a few more flags which are also defined in the |
612 | @file{glob.h} file. Some of the extensions implement functionality | |
613 | which is available in modern shell implementations. | |
614 | ||
0fc95b82 | 615 | @vtable @code |
714a562f UD |
616 | @comment glob.h |
617 | @comment GNU | |
618 | @item GLOB_PERIOD | |
619 | The @code{.} character (period) is treated special. It cannot be | |
620 | matched by wildcards. @xref{Wildcard Matching}, @code{FNM_PERIOD}. | |
621 | ||
622 | @comment glob.h | |
623 | @comment GNU | |
624 | @item GLOB_MAGCHAR | |
625 | The @code{GLOB_MAGCHAR} value is not to be given to @code{glob} in the | |
626 | @var{flags} parameter. Instead, @code{glob} sets this bit in the | |
627 | @var{gl_flags} element of the @var{glob_t} structure provided as the | |
628 | result if the pattern used for matching contains any wildcard character. | |
629 | ||
630 | @comment glob.h | |
631 | @comment GNU | |
632 | @item GLOB_ALTDIRFUNC | |
633 | Instead of the using the using the normal functions for accessing the | |
634 | filesystem the @code{glob} implementation uses the user-supplied | |
635 | functions specified in the structure pointed to by @var{pglob} | |
636 | parameter. For more information about the functions refer to the | |
8b7fb588 | 637 | sections about directory handling see @ref{Accessing Directories}, and |
714a562f UD |
638 | @ref{Reading Attributes}. |
639 | ||
640 | @comment glob.h | |
641 | @comment GNU | |
642 | @item GLOB_BRACE | |
643 | If this flag is given the handling of braces in the pattern is changed. | |
644 | It is now required that braces appear correctly grouped. I.e., for each | |
645 | opening brace there must be a closing one. Braces can be used | |
646 | recursively. So it is possible to define one brace expression in | |
647 | another one. It is important to note that the range of each brace | |
648 | expression is completely contained in the outer brace expression (if | |
649 | there is one). | |
650 | ||
f2ea0f5b | 651 | The string between the matching braces is separated into single |
714a562f | 652 | expressions by splitting at @code{,} (comma) characters. The commas |
0bc93a2f | 653 | themselves are discarded. Please note what we said above about recursive |
714a562f UD |
654 | brace expressions. The commas used to separate the subexpressions must |
655 | be at the same level. Commas in brace subexpressions are not matched. | |
656 | They are used during expansion of the brace expression of the deeper | |
657 | level. The example below shows this | |
658 | ||
659 | @smallexample | |
660 | glob ("@{foo/@{,bar,biz@},baz@}", GLOB_BRACE, NULL, &result) | |
661 | @end smallexample | |
662 | ||
663 | @noindent | |
664 | is equivalent to the sequence | |
665 | ||
666 | @smallexample | |
667 | glob ("foo/", GLOB_BRACE, NULL, &result) | |
668 | glob ("foo/bar", GLOB_BRACE|GLOB_APPEND, NULL, &result) | |
669 | glob ("foo/biz", GLOB_BRACE|GLOB_APPEND, NULL, &result) | |
670 | glob ("baz", GLOB_BRACE|GLOB_APPEND, NULL, &result) | |
671 | @end smallexample | |
672 | ||
673 | @noindent | |
674 | if we leave aside error handling. | |
675 | ||
676 | @comment glob.h | |
677 | @comment GNU | |
678 | @item GLOB_NOMAGIC | |
679 | If the pattern contains no wildcard constructs (it is a literal file name), | |
680 | return it as the sole ``matching'' word, even if no file exists by that name. | |
681 | ||
682 | @comment glob.h | |
683 | @comment GNU | |
684 | @item GLOB_TILDE | |
685 | If this flag is used the character @code{~} (tilde) is handled special | |
686 | if it appears at the beginning of the pattern. Instead of being taken | |
687 | verbatim it is used to represent the home directory of a known user. | |
688 | ||
689 | If @code{~} is the only character in pattern or it is followed by a | |
690 | @code{/} (slash), the home directory of the process owner is | |
691 | substituted. Using @code{getlogin} and @code{getpwnam} the information | |
692 | is read from the system databases. As an example take user @code{bart} | |
693 | with his home directory at @file{/home/bart}. For him a call like | |
694 | ||
695 | @smallexample | |
696 | glob ("~/bin/*", GLOB_TILDE, NULL, &result) | |
697 | @end smallexample | |
698 | ||
699 | @noindent | |
700 | would return the contents of the directory @file{/home/bart/bin}. | |
701 | Instead of referring to the own home directory it is also possible to | |
702 | name the home directory of other users. To do so one has to append the | |
703 | user name after the tilde character. So the contents of user | |
704 | @code{homer}'s @file{bin} directory can be retrieved by | |
705 | ||
706 | @smallexample | |
707 | glob ("~homer/bin/*", GLOB_TILDE, NULL, &result) | |
708 | @end smallexample | |
709 | ||
1bc21e7a UD |
710 | If the user name is not valid or the home directory cannot be determined |
711 | for some reason the pattern is left untouched and itself used as the | |
712 | result. I.e., if in the last example @code{home} is not available the | |
713 | tilde expansion yields to @code{"~homer/bin/*"} and @code{glob} is not | |
714 | looking for a directory named @code{~homer}. | |
715 | ||
716 | This functionality is equivalent to what is available in C-shells if the | |
717 | @code{nonomatch} flag is set. | |
718 | ||
719 | @comment glob.h | |
720 | @comment GNU | |
721 | @item GLOB_TILDE_CHECK | |
722 | If this flag is used @code{glob} behaves like as if @code{GLOB_TILDE} is | |
723 | given. The only difference is that if the user name is not available or | |
724 | the home directory cannot be determined for other reasons this leads to | |
725 | an error. @code{glob} will return @code{GLOB_NOMATCH} instead of using | |
726 | the pattern itself as the name. | |
727 | ||
ec986e23 | 728 | This functionality is equivalent to what is available in C-shells if |
1bc21e7a | 729 | @code{nonomatch} flag is not set. |
1cab5444 UD |
730 | |
731 | @comment glob.h | |
732 | @comment GNU | |
733 | @item GLOB_ONLYDIR | |
734 | If this flag is used the globbing function takes this as a | |
735 | @strong{hint} that the caller is only interested in directories | |
736 | matching the pattern. If the information about the type of the file | |
737 | is easily available non-directories will be rejected but no extra | |
738 | work will be done to determine the information for each file. I.e., | |
739 | the caller must still be able to filter directories out. | |
740 | ||
cc3fa755 | 741 | This functionality is only available with the GNU @code{glob} |
1cab5444 UD |
742 | implementation. It is mainly used internally to increase the |
743 | performance but might be useful for a user as well and therefore is | |
744 | documented here. | |
0fc95b82 | 745 | @end vtable |
714a562f | 746 | |
af6f3906 UD |
747 | Calling @code{glob} will in most cases allocate resources which are used |
748 | to represent the result of the function call. If the same object of | |
749 | type @code{glob_t} is used in multiple call to @code{glob} the resources | |
750 | are freed or reused so that no leaks appear. But this does not include | |
751 | the time when all @code{glob} calls are done. | |
752 | ||
753 | @comment glob.h | |
754 | @comment POSIX.2 | |
755 | @deftypefun void globfree (glob_t *@var{pglob}) | |
03483ada AO |
756 | @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}} |
757 | @c globfree dup @asucorrupt @ascuheap @acucorrupt @acsmem | |
758 | @c free dup @ascuheap @acsmem | |
af6f3906 UD |
759 | The @code{globfree} function frees all resources allocated by previous |
760 | calls to @code{glob} associated with the object pointed to by | |
761 | @var{pglob}. This function should be called whenever the currently used | |
762 | @code{glob_t} typed object isn't used anymore. | |
763 | @end deftypefun | |
764 | ||
0fc95b82 UD |
765 | @comment glob.h |
766 | @comment GNU | |
767 | @deftypefun void globfree64 (glob64_t *@var{pglob}) | |
03483ada | 768 | @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}} |
0fc95b82 UD |
769 | This function is equivalent to @code{globfree} but it frees records of |
770 | type @code{glob64_t} which were allocated by @code{glob64}. | |
771 | @end deftypefun | |
772 | ||
714a562f | 773 | |
28f540f4 RM |
774 | @node Regular Expressions |
775 | @section Regular Expression Matching | |
776 | ||
1f77f049 | 777 | @Theglibc{} supports two interfaces for matching regular |
28f540f4 | 778 | expressions. One is the standard POSIX.2 interface, and the other is |
a7a93d50 | 779 | what @theglibc{} has had for many years. |
28f540f4 RM |
780 | |
781 | Both interfaces are declared in the header file @file{regex.h}. | |
782 | If you define @w{@code{_POSIX_C_SOURCE}}, then only the POSIX.2 | |
783 | functions, structures, and constants are declared. | |
784 | @c !!! we only document the POSIX.2 interface here!! | |
785 | ||
786 | @menu | |
787 | * POSIX Regexp Compilation:: Using @code{regcomp} to prepare to match. | |
788 | * Flags for POSIX Regexps:: Syntax variations for @code{regcomp}. | |
789 | * Matching POSIX Regexps:: Using @code{regexec} to match the compiled | |
790 | pattern that you get from @code{regcomp}. | |
791 | * Regexp Subexpressions:: Finding which parts of the string were matched. | |
792 | * Subexpression Complications:: Find points of which parts were matched. | |
793 | * Regexp Cleanup:: Freeing storage; reporting errors. | |
794 | @end menu | |
795 | ||
796 | @node POSIX Regexp Compilation | |
797 | @subsection POSIX Regular Expression Compilation | |
798 | ||
799 | Before you can actually match a regular expression, you must | |
800 | @dfn{compile} it. This is not true compilation---it produces a special | |
801 | data structure, not machine instructions. But it is like ordinary | |
802 | compilation in that its purpose is to enable you to ``execute'' the | |
803 | pattern fast. (@xref{Matching POSIX Regexps}, for how to use the | |
804 | compiled regular expression for matching.) | |
805 | ||
806 | There is a special data type for compiled regular expressions: | |
807 | ||
808 | @comment regex.h | |
809 | @comment POSIX.2 | |
810 | @deftp {Data Type} regex_t | |
811 | This type of object holds a compiled regular expression. | |
812 | It is actually a structure. It has just one field that your programs | |
813 | should look at: | |
814 | ||
815 | @table @code | |
816 | @item re_nsub | |
817 | This field holds the number of parenthetical subexpressions in the | |
818 | regular expression that was compiled. | |
819 | @end table | |
820 | ||
821 | There are several other fields, but we don't describe them here, because | |
822 | only the functions in the library should use them. | |
823 | @end deftp | |
824 | ||
825 | After you create a @code{regex_t} object, you can compile a regular | |
826 | expression into it by calling @code{regcomp}. | |
827 | ||
828 | @comment regex.h | |
829 | @comment POSIX.2 | |
2d87db5b | 830 | @deftypefun int regcomp (regex_t *restrict @var{compiled}, const char *restrict @var{pattern}, int @var{cflags}) |
03483ada AO |
831 | @safety{@prelim{}@mtsafe{@mtslocale{}}@asunsafe{@asucorrupt{} @ascuheap{} @asulock{} @ascudlopen{}}@acunsafe{@acucorrupt{} @aculock{} @acsmem{} @acsfd{}}} |
832 | @c All of the issues have to do with memory allocation and multi-byte | |
833 | @c character handling present in the input string, or implied by ranges | |
834 | @c or inverted character classes. | |
835 | @c (re_)malloc @ascuheap @acsmem | |
836 | @c re_compile_internal @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
837 | @c (re_)realloc @ascuheap @acsmem [no @asucorrupt @acucorrupt for we zero the buffer] | |
838 | @c init_dfa @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
839 | @c (re_)malloc @ascuheap @acsmem | |
840 | @c calloc @ascuheap @acsmem | |
841 | @c _NL_CURRENT ok | |
842 | @c _NL_CURRENT_WORD ok | |
843 | @c btowc @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
844 | @c libc_lock_init ok | |
845 | @c re_string_construct @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
846 | @c re_string_construct_common ok | |
847 | @c re_string_realloc_buffers @ascuheap @acsmem | |
848 | @c (re_)realloc dup @ascuheap @acsmem | |
849 | @c build_wcs_upper_buffer @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
850 | @c isascii ok | |
851 | @c mbsinit ok | |
852 | @c toupper ok | |
853 | @c mbrtowc dup @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
854 | @c iswlower @mtslocale | |
855 | @c towupper @mtslocale | |
856 | @c wcrtomb dup @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
857 | @c (re_)malloc dup @ascuheap @acsmem | |
858 | @c build_upper_buffer ok (@mtslocale but optimized) | |
859 | @c islower ok | |
860 | @c toupper ok | |
861 | @c build_wcs_buffer @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
862 | @c mbrtowc dup @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
863 | @c re_string_translate_buffer ok | |
864 | @c parse @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
865 | @c fetch_token @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
866 | @c peek_token @mtslocale | |
867 | @c re_string_eoi ok | |
868 | @c re_string_peek_byte ok | |
869 | @c re_string_cur_idx ok | |
870 | @c re_string_length ok | |
871 | @c re_string_peek_byte_case @mtslocale | |
872 | @c re_string_peek_byte dup ok | |
873 | @c re_string_is_single_byte_char ok | |
874 | @c isascii ok | |
875 | @c re_string_peek_byte dup ok | |
876 | @c re_string_wchar_at ok | |
877 | @c re_string_skip_bytes ok | |
878 | @c re_string_skip_bytes dup ok | |
879 | @c parse_reg_exp @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
880 | @c parse_branch @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
881 | @c parse_expression @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
882 | @c create_token_tree dup @ascuheap @acsmem | |
883 | @c re_string_eoi dup ok | |
884 | @c re_string_first_byte ok | |
885 | @c fetch_token dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
886 | @c create_tree dup @ascuheap @acsmem | |
887 | @c parse_sub_exp @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
888 | @c fetch_token dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
889 | @c parse_reg_exp dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
890 | @c postorder() @ascuheap @acsmem | |
891 | @c free_tree @ascuheap @acsmem | |
892 | @c free_token dup @ascuheap @acsmem | |
893 | @c create_tree dup @ascuheap @acsmem | |
894 | @c parse_bracket_exp @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
895 | @c _NL_CURRENT dup ok | |
896 | @c _NL_CURRENT_WORD dup ok | |
897 | @c calloc dup @ascuheap @acsmem | |
898 | @c (re_)free dup @ascuheap @acsmem | |
899 | @c peek_token_bracket ok | |
900 | @c re_string_eoi dup ok | |
901 | @c re_string_peek_byte dup ok | |
902 | @c re_string_first_byte dup ok | |
903 | @c re_string_cur_idx dup ok | |
904 | @c re_string_length dup ok | |
905 | @c re_string_skip_bytes dup ok | |
906 | @c bitset_set ok | |
907 | @c re_string_skip_bytes ok | |
908 | @c parse_bracket_element @mtslocale | |
909 | @c re_string_char_size_at ok | |
910 | @c re_string_wchar_at dup ok | |
911 | @c re_string_skip_bytes dup ok | |
912 | @c parse_bracket_symbol @mtslocale | |
913 | @c re_string_eoi dup ok | |
914 | @c re_string_fetch_byte_case @mtslocale | |
915 | @c re_string_fetch_byte ok | |
916 | @c re_string_first_byte dup ok | |
917 | @c isascii ok | |
918 | @c re_string_char_size_at dup ok | |
919 | @c re_string_skip_bytes dup ok | |
920 | @c re_string_fetch_byte dup ok | |
921 | @c re_string_peek_byte dup ok | |
922 | @c re_string_skip_bytes dup ok | |
923 | @c peek_token_bracket dup ok | |
924 | @c auto build_range_exp @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
925 | @c auto lookup_collation_sequence_value @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
926 | @c btowc dup @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
927 | @c collseq_table_lookup ok | |
928 | @c auto seek_collating_symbol_entry dup ok | |
929 | @c (re_)realloc dup @ascuheap @acsmem | |
930 | @c collseq_table_lookup dup ok | |
931 | @c bitset_set dup ok | |
932 | @c (re_)realloc dup @ascuheap @acsmem | |
933 | @c build_equiv_class @mtslocale @ascuheap @acsmem | |
934 | @c _NL_CURRENT ok | |
935 | @c auto findidx ok | |
936 | @c bitset_set dup ok | |
937 | @c (re_)realloc dup @ascuheap @acsmem | |
938 | @c auto build_collating_symbol @ascuheap @acsmem | |
939 | @c auto seek_collating_symbol_entry ok | |
940 | @c bitset_set dup ok | |
941 | @c (re_)realloc dup @ascuheap @acsmem | |
942 | @c build_charclass @mtslocale @ascuheap @acsmem | |
943 | @c (re_)realloc dup @ascuheap @acsmem | |
944 | @c bitset_set dup ok | |
945 | @c isalnum ok | |
946 | @c iscntrl ok | |
947 | @c isspace ok | |
948 | @c isalpha ok | |
949 | @c isdigit ok | |
950 | @c isprint ok | |
951 | @c isupper ok | |
952 | @c isblank ok | |
953 | @c isgraph ok | |
954 | @c ispunct ok | |
955 | @c isxdigit ok | |
956 | @c bitset_not ok | |
957 | @c bitset_mask ok | |
958 | @c create_token_tree dup @ascuheap @acsmem | |
959 | @c create_tree dup @ascuheap @acsmem | |
960 | @c free_charset dup @ascuheap @acsmem | |
961 | @c init_word_char @mtslocale | |
962 | @c isalnum ok | |
963 | @c build_charclass_op @mtslocale @ascuheap @acsmem | |
964 | @c calloc dup @ascuheap @acsmem | |
965 | @c build_charclass dup @mtslocale @ascuheap @acsmem | |
966 | @c (re_)free dup @ascuheap @acsmem | |
967 | @c free_charset dup @ascuheap @acsmem | |
968 | @c bitset_set dup ok | |
969 | @c bitset_not dup ok | |
970 | @c bitset_mask dup ok | |
971 | @c create_token_tree dup @ascuheap @acsmem | |
972 | @c create_tree dup @ascuheap @acsmem | |
973 | @c parse_dup_op @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
974 | @c re_string_cur_idx dup ok | |
975 | @c fetch_number @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
976 | @c fetch_token dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
977 | @c re_string_set_index ok | |
978 | @c postorder() @ascuheap @acsmem | |
979 | @c free_tree dup @ascuheap @acsmem | |
980 | @c mark_opt_subexp ok | |
981 | @c duplicate_tree @ascuheap @acsmem | |
982 | @c create_token_tree dup @ascuheap @acsmem | |
983 | @c create_tree dup @ascuheap @acsmem | |
984 | @c postorder() @ascuheap @acsmem | |
985 | @c free_tree dup @ascuheap @acsmem | |
986 | @c fetch_token dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
987 | @c parse_branch dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
988 | @c create_tree dup @ascuheap @acsmem | |
989 | @c create_tree @ascuheap @acsmem | |
990 | @c create_token_tree @ascuheap @acsmem | |
991 | @c (re_)malloc dup @ascuheap @acsmem | |
992 | @c analyze @ascuheap @acsmem | |
993 | @c (re_)malloc dup @ascuheap @acsmem | |
994 | @c preorder() @ascuheap @acsmem | |
995 | @c optimize_subexps ok | |
996 | @c calc_next ok | |
997 | @c link_nfa_nodes @ascuheap @acsmem | |
998 | @c re_node_set_init_1 @ascuheap @acsmem | |
999 | @c (re_)malloc dup @ascuheap @acsmem | |
1000 | @c re_node_set_init_2 @ascuheap @acsmem | |
1001 | @c (re_)malloc dup @ascuheap @acsmem | |
1002 | @c postorder() @ascuheap @acsmem | |
1003 | @c lower_subexps @ascuheap @acsmem | |
1004 | @c lower_subexp @ascuheap @acsmem | |
1005 | @c create_tree dup @ascuheap @acsmem | |
1006 | @c calc_first @ascuheap @acsmem | |
1007 | @c re_dfa_add_node @ascuheap @acsmem | |
1008 | @c (re_)realloc dup @ascuheap @acsmem | |
1009 | @c re_node_set_init_empty ok | |
1010 | @c calc_eclosure @ascuheap @acsmem | |
1011 | @c calc_eclosure_iter @ascuheap @acsmem | |
1012 | @c re_node_set_alloc @ascuheap @acsmem | |
1013 | @c (re_)malloc dup @ascuheap @acsmem | |
1014 | @c duplicate_node_closure @ascuheap @acsmem | |
1015 | @c re_node_set_empty ok | |
1016 | @c duplicate_node @ascuheap @acsmem | |
1017 | @c re_dfa_add_node dup @ascuheap @acsmem | |
1018 | @c re_node_set_insert @ascuheap @acsmem | |
1019 | @c (re_)realloc dup @ascuheap @acsmem | |
1020 | @c search_duplicated_node ok | |
1021 | @c re_node_set_merge @ascuheap @acsmem | |
1022 | @c (re_)realloc dup @ascuheap @acsmem | |
1023 | @c re_node_set_free @ascuheap @acsmem | |
1024 | @c (re_)free dup @ascuheap @acsmem | |
1025 | @c re_node_set_insert dup @ascuheap @acsmem | |
1026 | @c re_node_set_free dup @ascuheap @acsmem | |
1027 | @c calc_inveclosure @ascuheap @acsmem | |
1028 | @c re_node_set_init_empty dup ok | |
1029 | @c re_node_set_insert_last @ascuheap @acsmem | |
1030 | @c (re_)realloc dup @ascuheap @acsmem | |
1031 | @c optimize_utf8 ok | |
1032 | @c create_initial_state @ascuheap @acsmem | |
1033 | @c re_node_set_init_copy @ascuheap @acsmem | |
1034 | @c (re_)malloc dup @ascuheap @acsmem | |
1035 | @c re_node_set_init_empty dup ok | |
1036 | @c re_node_set_contains ok | |
1037 | @c re_node_set_merge dup @ascuheap @acsmem | |
1038 | @c re_acquire_state_context @ascuheap @acsmem | |
1039 | @c calc_state_hash ok | |
1040 | @c re_node_set_compare ok | |
1041 | @c create_cd_newstate @ascuheap @acsmem | |
1042 | @c calloc dup @ascuheap @acsmem | |
1043 | @c re_node_set_init_copy dup @ascuheap @acsmem | |
1044 | @c (re_)free dup @ascuheap @acsmem | |
1045 | @c free_state @ascuheap @acsmem | |
1046 | @c re_node_set_free dup @ascuheap @acsmem | |
1047 | @c (re_)free dup @ascuheap @acsmem | |
1048 | @c NOT_SATISFY_PREV_CONSTRAINT ok | |
1049 | @c re_node_set_remove_at ok | |
1050 | @c register_state @ascuheap @acsmem | |
1051 | @c re_node_set_alloc dup @ascuheap @acsmem | |
1052 | @c re_node_set_insert_last dup @ascuheap @acsmem | |
1053 | @c (re_)realloc dup @ascuheap @acsmem | |
1054 | @c re_node_set_free dup @ascuheap @acsmem | |
1055 | @c free_workarea_compile @ascuheap @acsmem | |
1056 | @c (re_)free dup @ascuheap @acsmem | |
1057 | @c re_string_destruct @ascuheap @acsmem | |
1058 | @c (re_)free dup @ascuheap @acsmem | |
1059 | @c free_dfa_content @ascuheap @acsmem | |
1060 | @c free_token @ascuheap @acsmem | |
1061 | @c free_charset @ascuheap @acsmem | |
1062 | @c (re_)free dup @ascuheap @acsmem | |
1063 | @c (re_)free dup @ascuheap @acsmem | |
1064 | @c (re_)free dup @ascuheap @acsmem | |
1065 | @c re_node_set_free dup @ascuheap @acsmem | |
1066 | @c re_compile_fastmap @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1067 | @c re_compile_fastmap_iter @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1068 | @c re_set_fastmap ok | |
1069 | @c tolower ok | |
1070 | @c mbrtowc dup @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1071 | @c wcrtomb dup @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1072 | @c towlower @mtslocale | |
1073 | @c _NL_CURRENT ok | |
1074 | @c (re_)free @ascuheap @acsmem | |
28f540f4 RM |
1075 | The function @code{regcomp} ``compiles'' a regular expression into a |
1076 | data structure that you can use with @code{regexec} to match against a | |
1077 | string. The compiled regular expression format is designed for | |
1078 | efficient matching. @code{regcomp} stores it into @code{*@var{compiled}}. | |
1079 | ||
1080 | It's up to you to allocate an object of type @code{regex_t} and pass its | |
1081 | address to @code{regcomp}. | |
1082 | ||
1083 | The argument @var{cflags} lets you specify various options that control | |
1084 | the syntax and semantics of regular expressions. @xref{Flags for POSIX | |
1085 | Regexps}. | |
1086 | ||
1087 | If you use the flag @code{REG_NOSUB}, then @code{regcomp} omits from | |
1088 | the compiled regular expression the information necessary to record | |
1089 | how subexpressions actually match. In this case, you might as well | |
1090 | pass @code{0} for the @var{matchptr} and @var{nmatch} arguments when | |
1091 | you call @code{regexec}. | |
1092 | ||
1093 | If you don't use @code{REG_NOSUB}, then the compiled regular expression | |
1094 | does have the capacity to record how subexpressions match. Also, | |
1095 | @code{regcomp} tells you how many subexpressions @var{pattern} has, by | |
1096 | storing the number in @code{@var{compiled}->re_nsub}. You can use that | |
1097 | value to decide how long an array to allocate to hold information about | |
1098 | subexpression matches. | |
1099 | ||
1100 | @code{regcomp} returns @code{0} if it succeeds in compiling the regular | |
1101 | expression; otherwise, it returns a nonzero error code (see the table | |
1102 | below). You can use @code{regerror} to produce an error message string | |
1103 | describing the reason for a nonzero value; see @ref{Regexp Cleanup}. | |
1104 | ||
1105 | @end deftypefun | |
1106 | ||
1107 | Here are the possible nonzero values that @code{regcomp} can return: | |
1108 | ||
1109 | @table @code | |
1110 | @comment regex.h | |
1111 | @comment POSIX.2 | |
1112 | @item REG_BADBR | |
1113 | There was an invalid @samp{\@{@dots{}\@}} construct in the regular | |
1114 | expression. A valid @samp{\@{@dots{}\@}} construct must contain either | |
1115 | a single number, or two numbers in increasing order separated by a | |
1116 | comma. | |
1117 | ||
1118 | @comment regex.h | |
1119 | @comment POSIX.2 | |
1120 | @item REG_BADPAT | |
1121 | There was a syntax error in the regular expression. | |
1122 | ||
1123 | @comment regex.h | |
1124 | @comment POSIX.2 | |
1125 | @item REG_BADRPT | |
1126 | A repetition operator such as @samp{?} or @samp{*} appeared in a bad | |
1127 | position (with no preceding subexpression to act on). | |
1128 | ||
1129 | @comment regex.h | |
1130 | @comment POSIX.2 | |
1131 | @item REG_ECOLLATE | |
1132 | The regular expression referred to an invalid collating element (one not | |
1133 | defined in the current locale for string collation). @xref{Locale | |
1134 | Categories}. | |
1135 | ||
1136 | @comment regex.h | |
1137 | @comment POSIX.2 | |
1138 | @item REG_ECTYPE | |
1139 | The regular expression referred to an invalid character class name. | |
1140 | ||
1141 | @comment regex.h | |
1142 | @comment POSIX.2 | |
1143 | @item REG_EESCAPE | |
1144 | The regular expression ended with @samp{\}. | |
1145 | ||
1146 | @comment regex.h | |
1147 | @comment POSIX.2 | |
1148 | @item REG_ESUBREG | |
1149 | There was an invalid number in the @samp{\@var{digit}} construct. | |
1150 | ||
1151 | @comment regex.h | |
1152 | @comment POSIX.2 | |
1153 | @item REG_EBRACK | |
1154 | There were unbalanced square brackets in the regular expression. | |
1155 | ||
1156 | @comment regex.h | |
1157 | @comment POSIX.2 | |
1158 | @item REG_EPAREN | |
1159 | An extended regular expression had unbalanced parentheses, | |
1160 | or a basic regular expression had unbalanced @samp{\(} and @samp{\)}. | |
1161 | ||
1162 | @comment regex.h | |
1163 | @comment POSIX.2 | |
1164 | @item REG_EBRACE | |
1165 | The regular expression had unbalanced @samp{\@{} and @samp{\@}}. | |
1166 | ||
1167 | @comment regex.h | |
1168 | @comment POSIX.2 | |
1169 | @item REG_ERANGE | |
1170 | One of the endpoints in a range expression was invalid. | |
1171 | ||
1172 | @comment regex.h | |
1173 | @comment POSIX.2 | |
1174 | @item REG_ESPACE | |
1175 | @code{regcomp} ran out of memory. | |
1176 | @end table | |
1177 | ||
1178 | @node Flags for POSIX Regexps | |
1179 | @subsection Flags for POSIX Regular Expressions | |
1180 | ||
1181 | These are the bit flags that you can use in the @var{cflags} operand when | |
1182 | compiling a regular expression with @code{regcomp}. | |
6d52618b | 1183 | |
28f540f4 RM |
1184 | @table @code |
1185 | @comment regex.h | |
1186 | @comment POSIX.2 | |
1187 | @item REG_EXTENDED | |
1188 | Treat the pattern as an extended regular expression, rather than as a | |
1189 | basic regular expression. | |
1190 | ||
1191 | @comment regex.h | |
1192 | @comment POSIX.2 | |
1193 | @item REG_ICASE | |
1194 | Ignore case when matching letters. | |
1195 | ||
1196 | @comment regex.h | |
1197 | @comment POSIX.2 | |
1198 | @item REG_NOSUB | |
1199 | Don't bother storing the contents of the @var{matches-ptr} array. | |
1200 | ||
1201 | @comment regex.h | |
1202 | @comment POSIX.2 | |
1203 | @item REG_NEWLINE | |
1204 | Treat a newline in @var{string} as dividing @var{string} into multiple | |
1205 | lines, so that @samp{$} can match before the newline and @samp{^} can | |
1206 | match after. Also, don't permit @samp{.} to match a newline, and don't | |
1207 | permit @samp{[^@dots{}]} to match a newline. | |
1208 | ||
1209 | Otherwise, newline acts like any other ordinary character. | |
1210 | @end table | |
1211 | ||
1212 | @node Matching POSIX Regexps | |
1213 | @subsection Matching a Compiled POSIX Regular Expression | |
1214 | ||
1215 | Once you have compiled a regular expression, as described in @ref{POSIX | |
1216 | Regexp Compilation}, you can match it against strings using | |
1217 | @code{regexec}. A match anywhere inside the string counts as success, | |
1218 | unless the regular expression contains anchor characters (@samp{^} or | |
1219 | @samp{$}). | |
1220 | ||
1221 | @comment regex.h | |
1222 | @comment POSIX.2 | |
2d87db5b | 1223 | @deftypefun int regexec (const regex_t *restrict @var{compiled}, const char *restrict @var{string}, size_t @var{nmatch}, regmatch_t @var{matchptr}[restrict], int @var{eflags}) |
03483ada AO |
1224 | @safety{@prelim{}@mtsafe{@mtslocale{}}@asunsafe{@asucorrupt{} @ascuheap{} @asulock{} @ascudlopen{}}@acunsafe{@acucorrupt{} @aculock{} @acsmem{} @acsfd{}}} |
1225 | @c libc_lock_lock @asulock @aculock | |
1226 | @c re_search_internal @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1227 | @c re_string_allocate @ascuheap @acsmem | |
1228 | @c re_string_construct_common dup ok | |
1229 | @c re_string_realloc_buffers dup @ascuheap @acsmem | |
1230 | @c match_ctx_init @ascuheap @acsmem | |
1231 | @c (re_)malloc dup @ascuheap @acsmem | |
1232 | @c re_string_byte_at ok | |
1233 | @c re_string_first_byte dup ok | |
1234 | @c check_matching @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1235 | @c re_string_cur_idx dup ok | |
1236 | @c acquire_init_state_context dup @ascuheap @acsmem | |
1237 | @c re_string_context_at ok | |
1238 | @c re_string_byte_at dup ok | |
1239 | @c bitset_contain ok | |
1240 | @c re_acquire_state_context dup @ascuheap @acsmem | |
1241 | @c check_subexp_matching_top @ascuheap @acsmem | |
1242 | @c match_ctx_add_subtop @ascuheap @acsmem | |
1243 | @c (re_)realloc dup @ascuheap @acsmem | |
1244 | @c calloc dup @ascuheap @acsmem | |
1245 | @c transit_state_bkref @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1246 | @c re_string_cur_idx dup ok | |
1247 | @c re_string_context_at dup ok | |
1248 | @c NOT_SATISFY_NEXT_CONSTRAINT ok | |
1249 | @c get_subexp @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1250 | @c re_string_get_buffer ok | |
1251 | @c search_cur_bkref_entry ok | |
1252 | @c clean_state_log_if_needed @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1253 | @c extend_buffers @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1254 | @c re_string_realloc_buffers dup @ascuheap @acsmem | |
1255 | @c (re_)realloc dup @ascuheap @acsmem | |
1256 | @c build_wcs_upper_buffer dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1257 | @c build_upper_buffer dup ok (@mtslocale but optimized) | |
1258 | @c build_wcs_buffer dup @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1259 | @c re_string_translate_buffer dup ok | |
1260 | @c get_subexp_sub @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1261 | @c check_arrival @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1262 | @c (re_)realloc dup @ascuheap @acsmem | |
1263 | @c re_string_context_at dup ok | |
1264 | @c re_node_set_init_1 dup @ascuheap @acsmem | |
1265 | @c check_arrival_expand_ecl @ascuheap @acsmem | |
1266 | @c re_node_set_alloc dup @ascuheap @acsmem | |
1267 | @c find_subexp_node ok | |
1268 | @c re_node_set_merge dup @ascuheap @acsmem | |
1269 | @c re_node_set_free dup @ascuheap @acsmem | |
1270 | @c check_arrival_expand_ecl_sub @ascuheap @acsmem | |
1271 | @c re_node_set_contains dup ok | |
1272 | @c re_node_set_insert dup @ascuheap @acsmem | |
1273 | @c re_node_set_free dup @ascuheap @acsmem | |
1274 | @c re_node_set_init_copy dup @ascuheap @acsmem | |
1275 | @c re_node_set_init_empty dup ok | |
1276 | @c expand_bkref_cache @ascuheap @acsmem | |
1277 | @c search_cur_bkref_entry dup ok | |
1278 | @c re_node_set_contains dup ok | |
1279 | @c re_node_set_init_1 dup @ascuheap @acsmem | |
1280 | @c check_arrival_expand_ecl dup @ascuheap @acsmem | |
1281 | @c re_node_set_merge dup @ascuheap @acsmem | |
1282 | @c re_node_set_init_copy dup @ascuheap @acsmem | |
1283 | @c re_node_set_insert dup @ascuheap @acsmem | |
1284 | @c re_node_set_free dup @ascuheap @acsmem | |
1285 | @c re_acquire_state @ascuheap @acsmem | |
1286 | @c calc_state_hash dup ok | |
1287 | @c re_node_set_compare dup ok | |
1288 | @c create_ci_newstate @ascuheap @acsmem | |
1289 | @c calloc dup @ascuheap @acsmem | |
1290 | @c re_node_set_init_copy dup @ascuheap @acsmem | |
1291 | @c (re_)free dup @ascuheap @acsmem | |
1292 | @c register_state dup @ascuheap @acsmem | |
1293 | @c free_state dup @ascuheap @acsmem | |
1294 | @c re_acquire_state_context dup @ascuheap @acsmem | |
1295 | @c re_node_set_merge dup @ascuheap @acsmem | |
1296 | @c check_arrival_add_next_nodes @mtslocale @ascuheap @acsmem | |
1297 | @c re_node_set_init_empty dup ok | |
1298 | @c check_node_accept_bytes @mtslocale @ascuheap @acsmem | |
1299 | @c re_string_byte_at dup ok | |
1300 | @c re_string_char_size_at dup ok | |
1301 | @c re_string_elem_size_at @mtslocale | |
1302 | @c _NL_CURRENT_WORD dup ok | |
1303 | @c _NL_CURRENT dup ok | |
1304 | @c auto findidx dup ok | |
1305 | @c _NL_CURRENT_WORD dup ok | |
1306 | @c _NL_CURRENT dup ok | |
1307 | @c collseq_table_lookup dup ok | |
1308 | @c find_collation_sequence_value @mtslocale | |
1309 | @c _NL_CURRENT_WORD dup ok | |
1310 | @c _NL_CURRENT dup ok | |
1311 | @c auto findidx dup ok | |
1312 | @c wcscoll @mtslocale @ascuheap @acsmem | |
1313 | @c re_node_set_empty dup ok | |
1314 | @c re_node_set_merge dup @ascuheap @acsmem | |
1315 | @c re_node_set_free dup @ascuheap @acsmem | |
1316 | @c re_node_set_insert dup @ascuheap @acsmem | |
1317 | @c re_acquire_state dup @ascuheap @acsmem | |
1318 | @c check_node_accept ok | |
1319 | @c re_string_byte_at dup ok | |
1320 | @c bitset_contain dup ok | |
1321 | @c re_string_context_at dup ok | |
1322 | @c NOT_SATISFY_NEXT_CONSTRAINT dup ok | |
1323 | @c match_ctx_add_entry @ascuheap @acsmem | |
1324 | @c (re_)realloc dup @ascuheap @acsmem | |
1325 | @c (re_)free dup @ascuheap @acsmem | |
1326 | @c clean_state_log_if_needed dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1327 | @c extend_buffers dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1328 | @c find_subexp_node dup ok | |
1329 | @c calloc dup @ascuheap @acsmem | |
1330 | @c check_arrival dup *** | |
1331 | @c match_ctx_add_sublast @ascuheap @acsmem | |
1332 | @c (re_)realloc dup @ascuheap @acsmem | |
1333 | @c re_acquire_state_context dup @ascuheap @acsmem | |
1334 | @c re_node_set_init_union @ascuheap @acsmem | |
1335 | @c (re_)malloc dup @ascuheap @acsmem | |
1336 | @c re_node_set_init_copy dup @ascuheap @acsmem | |
1337 | @c re_node_set_init_empty dup ok | |
1338 | @c re_node_set_free dup @ascuheap @acsmem | |
1339 | @c check_subexp_matching_top dup @ascuheap @acsmem | |
1340 | @c check_halt_state_context ok | |
1341 | @c re_string_context_at dup ok | |
1342 | @c check_halt_node_context ok | |
1343 | @c NOT_SATISFY_NEXT_CONSTRAINT dup ok | |
1344 | @c re_string_eoi dup ok | |
1345 | @c extend_buffers dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1346 | @c transit_state @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1347 | @c transit_state_mb @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1348 | @c re_string_context_at dup ok | |
1349 | @c NOT_SATISFY_NEXT_CONSTRAINT dup ok | |
1350 | @c check_node_accept_bytes dup @mtslocale @ascuheap @acsmem | |
1351 | @c re_string_cur_idx dup ok | |
1352 | @c clean_state_log_if_needed @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1353 | @c re_node_set_init_union dup @ascuheap @acsmem | |
1354 | @c re_acquire_state_context dup @ascuheap @acsmem | |
1355 | @c re_string_fetch_byte dup ok | |
1356 | @c re_string_context_at dup ok | |
1357 | @c build_trtable @ascuheap @acsmem | |
1358 | @c (re_)malloc dup @ascuheap @acsmem | |
1359 | @c group_nodes_into_DFAstates @ascuheap @acsmem | |
1360 | @c bitset_empty dup ok | |
1361 | @c bitset_set dup ok | |
1362 | @c bitset_merge dup ok | |
1363 | @c bitset_set_all ok | |
1364 | @c bitset_clear ok | |
1365 | @c bitset_contain dup ok | |
1366 | @c bitset_copy ok | |
1367 | @c re_node_set_init_copy dup @ascuheap @acsmem | |
1368 | @c re_node_set_insert dup @ascuheap @acsmem | |
1369 | @c re_node_set_init_1 dup @ascuheap @acsmem | |
1370 | @c re_node_set_free dup @ascuheap @acsmem | |
1371 | @c re_node_set_alloc dup @ascuheap @acsmem | |
1372 | @c malloc dup @ascuheap @acsmem | |
1373 | @c free dup @ascuheap @acsmem | |
1374 | @c re_node_set_free dup @ascuheap @acsmem | |
1375 | @c bitset_empty ok | |
1376 | @c re_node_set_empty dup ok | |
1377 | @c re_node_set_merge dup @ascuheap @acsmem | |
1378 | @c re_acquire_state_context dup @ascuheap @acsmem | |
1379 | @c bitset_merge ok | |
1380 | @c calloc dup @ascuheap @acsmem | |
1381 | @c bitset_contain dup ok | |
1382 | @c merge_state_with_log @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1383 | @c re_string_cur_idx dup ok | |
1384 | @c re_node_set_init_union dup @ascuheap @acsmem | |
1385 | @c re_string_context_at dup ok | |
1386 | @c re_node_set_free dup @ascuheap @acsmem | |
1387 | @c check_subexp_matching_top @ascuheap @acsmem | |
1388 | @c match_ctx_add_subtop dup @ascuheap @acsmem | |
1389 | @c transit_state_bkref dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1390 | @c find_recover_state | |
1391 | @c re_string_cur_idx dup ok | |
1392 | @c re_string_skip_bytes dup ok | |
1393 | @c merge_state_with_log dup @mtslocale @asucorrupt @ascuheap @asulock @ascudlopen @acucorrupt @aculock @acsmem @acsfd | |
1394 | @c check_halt_state_context dup ok | |
1395 | @c prune_impossible_nodes @mtslocale @ascuheap @acsmem | |
1396 | @c (re_)malloc dup @ascuheap @acsmem | |
1397 | @c sift_ctx_init ok | |
1398 | @c re_node_set_init_empty dup ok | |
1399 | @c sift_states_backward @mtslocale @ascuheap @acsmem | |
1400 | @c re_node_set_init_1 dup @ascuheap @acsmem | |
1401 | @c update_cur_sifted_state @mtslocale @ascuheap @acsmem | |
1402 | @c add_epsilon_src_nodes @ascuheap @acsmem | |
1403 | @c re_acquire_state dup @ascuheap @acsmem | |
1404 | @c re_node_set_alloc dup @ascuheap @acsmem | |
1405 | @c re_node_set_merge dup @ascuheap @acsmem | |
1406 | @c re_node_set_add_intersect @ascuheap @acsmem | |
1407 | @c (re_)realloc dup @ascuheap @acsmem | |
1408 | @c check_subexp_limits @ascuheap @acsmem | |
1409 | @c sub_epsilon_src_nodes @ascuheap @acsmem | |
1410 | @c re_node_set_init_empty dup ok | |
1411 | @c re_node_set_contains dup ok | |
1412 | @c re_node_set_add_intersect dup @ascuheap @acsmem | |
1413 | @c re_node_set_free dup @ascuheap @acsmem | |
1414 | @c re_node_set_remove_at dup ok | |
1415 | @c re_node_set_contains dup ok | |
1416 | @c re_acquire_state dup @ascuheap @acsmem | |
1417 | @c sift_states_bkref @mtslocale @ascuheap @acsmem | |
1418 | @c search_cur_bkref_entry dup ok | |
1419 | @c check_dst_limits ok | |
1420 | @c search_cur_bkref_entry dup ok | |
1421 | @c check_dst_limits_calc_pos ok | |
1422 | @c check_dst_limits_calc_pos_1 ok | |
1423 | @c re_node_set_init_copy dup @ascuheap @acsmem | |
1424 | @c re_node_set_insert dup @ascuheap @acsmem | |
1425 | @c sift_states_backward dup @mtslocale @ascuheap @acsmem | |
1426 | @c merge_state_array dup @ascuheap @acsmem | |
1427 | @c re_node_set_remove ok | |
1428 | @c re_node_set_contains dup ok | |
1429 | @c re_node_set_remove_at dup ok | |
1430 | @c re_node_set_free dup @ascuheap @acsmem | |
1431 | @c re_node_set_free dup @ascuheap @acsmem | |
1432 | @c re_node_set_empty dup ok | |
1433 | @c build_sifted_states @mtslocale @ascuheap @acsmem | |
1434 | @c sift_states_iter_mb @mtslocale @ascuheap @acsmem | |
1435 | @c check_node_accept_bytes dup @mtslocale @ascuheap @acsmem | |
1436 | @c check_node_accept dup ok | |
1437 | @c check_dst_limits dup ok | |
1438 | @c re_node_set_insert dup @ascuheap @acsmem | |
1439 | @c re_node_set_free dup @ascuheap @acsmem | |
1440 | @c check_halt_state_context dup ok | |
1441 | @c merge_state_array @ascuheap @acsmem | |
1442 | @c re_node_set_init_union dup @ascuheap @acsmem | |
1443 | @c re_acquire_state dup @ascuheap @acsmem | |
1444 | @c re_node_set_free dup @ascuheap @acsmem | |
1445 | @c (re_)free dup @ascuheap @acsmem | |
1446 | @c set_regs @ascuheap @acsmem | |
1447 | @c (re_)malloc dup @ascuheap @acsmem | |
1448 | @c re_node_set_init_empty dup ok | |
1449 | @c free_fail_stack_return @ascuheap @acsmem | |
1450 | @c re_node_set_free dup @ascuheap @acsmem | |
1451 | @c (re_)free dup @ascuheap @acsmem | |
1452 | @c update_regs ok | |
1453 | @c re_node_set_free dup @ascuheap @acsmem | |
1454 | @c pop_fail_stack @ascuheap @acsmem | |
1455 | @c re_node_set_free dup @ascuheap @acsmem | |
1456 | @c (re_)free dup @ascuheap @acsmem | |
1457 | @c (re_)free dup @ascuheap @acsmem | |
1458 | @c (re_)free dup @ascuheap @acsmem | |
1459 | @c match_ctx_free @ascuheap @acsmem | |
1460 | @c match_ctx_clean @ascuheap @acsmem | |
1461 | @c (re_)free dup @ascuheap @acsmem | |
1462 | @c (re_)free dup @ascuheap @acsmem | |
1463 | @c re_string_destruct dup @ascuheap @acsmem | |
1464 | @c libc_lock_unlock @aculock | |
28f540f4 RM |
1465 | This function tries to match the compiled regular expression |
1466 | @code{*@var{compiled}} against @var{string}. | |
1467 | ||
1468 | @code{regexec} returns @code{0} if the regular expression matches; | |
1469 | otherwise, it returns a nonzero value. See the table below for | |
1470 | what nonzero values mean. You can use @code{regerror} to produce an | |
6d52618b | 1471 | error message string describing the reason for a nonzero value; |
28f540f4 RM |
1472 | see @ref{Regexp Cleanup}. |
1473 | ||
1474 | The argument @var{eflags} is a word of bit flags that enable various | |
1475 | options. | |
1476 | ||
1477 | If you want to get information about what part of @var{string} actually | |
1478 | matched the regular expression or its subexpressions, use the arguments | |
6d52618b | 1479 | @var{matchptr} and @var{nmatch}. Otherwise, pass @code{0} for |
28f540f4 RM |
1480 | @var{nmatch}, and @code{NULL} for @var{matchptr}. @xref{Regexp |
1481 | Subexpressions}. | |
1482 | @end deftypefun | |
1483 | ||
1484 | You must match the regular expression with the same set of current | |
1485 | locales that were in effect when you compiled the regular expression. | |
1486 | ||
1487 | The function @code{regexec} accepts the following flags in the | |
1488 | @var{eflags} argument: | |
1489 | ||
6d52618b | 1490 | @table @code |
28f540f4 RM |
1491 | @comment regex.h |
1492 | @comment POSIX.2 | |
1493 | @item REG_NOTBOL | |
1494 | Do not regard the beginning of the specified string as the beginning of | |
1495 | a line; more generally, don't make any assumptions about what text might | |
1496 | precede it. | |
1497 | ||
1498 | @comment regex.h | |
1499 | @comment POSIX.2 | |
1500 | @item REG_NOTEOL | |
1501 | Do not regard the end of the specified string as the end of a line; more | |
1502 | generally, don't make any assumptions about what text might follow it. | |
1503 | @end table | |
1504 | ||
1505 | Here are the possible nonzero values that @code{regexec} can return: | |
1506 | ||
1507 | @table @code | |
1508 | @comment regex.h | |
1509 | @comment POSIX.2 | |
1510 | @item REG_NOMATCH | |
1511 | The pattern didn't match the string. This isn't really an error. | |
1512 | ||
1513 | @comment regex.h | |
1514 | @comment POSIX.2 | |
1515 | @item REG_ESPACE | |
1516 | @code{regexec} ran out of memory. | |
1517 | @end table | |
1518 | ||
1519 | @node Regexp Subexpressions | |
1520 | @subsection Match Results with Subexpressions | |
1521 | ||
1522 | When @code{regexec} matches parenthetical subexpressions of | |
1523 | @var{pattern}, it records which parts of @var{string} they match. It | |
1524 | returns that information by storing the offsets into an array whose | |
1525 | elements are structures of type @code{regmatch_t}. The first element of | |
1526 | the array (index @code{0}) records the part of the string that matched | |
1527 | the entire regular expression. Each other element of the array records | |
1528 | the beginning and end of the part that matched a single parenthetical | |
1529 | subexpression. | |
1530 | ||
1531 | @comment regex.h | |
1532 | @comment POSIX.2 | |
1533 | @deftp {Data Type} regmatch_t | |
1534 | This is the data type of the @var{matcharray} array that you pass to | |
6d52618b | 1535 | @code{regexec}. It contains two structure fields, as follows: |
28f540f4 RM |
1536 | |
1537 | @table @code | |
1538 | @item rm_so | |
1539 | The offset in @var{string} of the beginning of a substring. Add this | |
1540 | value to @var{string} to get the address of that part. | |
1541 | ||
1542 | @item rm_eo | |
1543 | The offset in @var{string} of the end of the substring. | |
1544 | @end table | |
1545 | @end deftp | |
1546 | ||
1547 | @comment regex.h | |
1548 | @comment POSIX.2 | |
1549 | @deftp {Data Type} regoff_t | |
1550 | @code{regoff_t} is an alias for another signed integer type. | |
1551 | The fields of @code{regmatch_t} have type @code{regoff_t}. | |
1552 | @end deftp | |
1553 | ||
1554 | The @code{regmatch_t} elements correspond to subexpressions | |
1555 | positionally; the first element (index @code{1}) records where the first | |
1556 | subexpression matched, the second element records the second | |
1557 | subexpression, and so on. The order of the subexpressions is the order | |
1558 | in which they begin. | |
1559 | ||
1560 | When you call @code{regexec}, you specify how long the @var{matchptr} | |
1561 | array is, with the @var{nmatch} argument. This tells @code{regexec} how | |
1562 | many elements to store. If the actual regular expression has more than | |
1563 | @var{nmatch} subexpressions, then you won't get offset information about | |
1564 | the rest of them. But this doesn't alter whether the pattern matches a | |
1565 | particular string or not. | |
1566 | ||
1567 | If you don't want @code{regexec} to return any information about where | |
1568 | the subexpressions matched, you can either supply @code{0} for | |
1569 | @var{nmatch}, or use the flag @code{REG_NOSUB} when you compile the | |
1570 | pattern with @code{regcomp}. | |
1571 | ||
1572 | @node Subexpression Complications | |
1573 | @subsection Complications in Subexpression Matching | |
1574 | ||
1575 | Sometimes a subexpression matches a substring of no characters. This | |
1576 | happens when @samp{f\(o*\)} matches the string @samp{fum}. (It really | |
1577 | matches just the @samp{f}.) In this case, both of the offsets identify | |
1578 | the point in the string where the null substring was found. In this | |
1579 | example, the offsets are both @code{1}. | |
1580 | ||
1581 | Sometimes the entire regular expression can match without using some of | |
1582 | its subexpressions at all---for example, when @samp{ba\(na\)*} matches the | |
1583 | string @samp{ba}, the parenthetical subexpression is not used. When | |
1584 | this happens, @code{regexec} stores @code{-1} in both fields of the | |
1585 | element for that subexpression. | |
1586 | ||
1587 | Sometimes matching the entire regular expression can match a particular | |
1588 | subexpression more than once---for example, when @samp{ba\(na\)*} | |
1589 | matches the string @samp{bananana}, the parenthetical subexpression | |
1590 | matches three times. When this happens, @code{regexec} usually stores | |
1591 | the offsets of the last part of the string that matched the | |
1592 | subexpression. In the case of @samp{bananana}, these offsets are | |
1593 | @code{6} and @code{8}. | |
1594 | ||
1595 | But the last match is not always the one that is chosen. It's more | |
1596 | accurate to say that the last @emph{opportunity} to match is the one | |
1597 | that takes precedence. What this means is that when one subexpression | |
1598 | appears within another, then the results reported for the inner | |
1599 | subexpression reflect whatever happened on the last match of the outer | |
1600 | subexpression. For an example, consider @samp{\(ba\(na\)*s \)*} matching | |
1601 | the string @samp{bananas bas }. The last time the inner expression | |
6d52618b | 1602 | actually matches is near the end of the first word. But it is |
28f540f4 RM |
1603 | @emph{considered} again in the second word, and fails to match there. |
1604 | @code{regexec} reports nonuse of the ``na'' subexpression. | |
1605 | ||
1606 | Another place where this rule applies is when the regular expression | |
838e5ffe UD |
1607 | @smallexample |
1608 | \(ba\(na\)*s \|nefer\(ti\)* \)* | |
1609 | @end smallexample | |
1610 | @noindent | |
1611 | matches @samp{bananas nefertiti}. The ``na'' subexpression does match | |
1612 | in the first word, but it doesn't match in the second word because the | |
1613 | other alternative is used there. Once again, the second repetition of | |
1614 | the outer subexpression overrides the first, and within that second | |
1615 | repetition, the ``na'' subexpression is not used. So @code{regexec} | |
1616 | reports nonuse of the ``na'' subexpression. | |
28f540f4 RM |
1617 | |
1618 | @node Regexp Cleanup | |
1619 | @subsection POSIX Regexp Matching Cleanup | |
1620 | ||
1621 | When you are finished using a compiled regular expression, you can | |
1622 | free the storage it uses by calling @code{regfree}. | |
1623 | ||
1624 | @comment regex.h | |
1625 | @comment POSIX.2 | |
1626 | @deftypefun void regfree (regex_t *@var{compiled}) | |
03483ada AO |
1627 | @safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}} |
1628 | @c (re_)free dup @ascuheap @acsmem | |
1629 | @c free_dfa_content dup @ascuheap @acsmem | |
28f540f4 RM |
1630 | Calling @code{regfree} frees all the storage that @code{*@var{compiled}} |
1631 | points to. This includes various internal fields of the @code{regex_t} | |
1632 | structure that aren't documented in this manual. | |
1633 | ||
1634 | @code{regfree} does not free the object @code{*@var{compiled}} itself. | |
1635 | @end deftypefun | |
1636 | ||
1637 | You should always free the space in a @code{regex_t} structure with | |
1638 | @code{regfree} before using the structure to compile another regular | |
1639 | expression. | |
1640 | ||
1641 | When @code{regcomp} or @code{regexec} reports an error, you can use | |
1642 | the function @code{regerror} to turn it into an error message string. | |
1643 | ||
1644 | @comment regex.h | |
1645 | @comment POSIX.2 | |
2d87db5b | 1646 | @deftypefun size_t regerror (int @var{errcode}, const regex_t *restrict @var{compiled}, char *restrict @var{buffer}, size_t @var{length}) |
03483ada AO |
1647 | @safety{@prelim{}@mtsafe{@mtsenv{}}@asunsafe{@asucorrupt{} @ascuheap{} @asulock{} @ascudlopen{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}} |
1648 | @c regerror calls gettext, strcmp and mempcpy or memcpy. | |
28f540f4 RM |
1649 | This function produces an error message string for the error code |
1650 | @var{errcode}, and stores the string in @var{length} bytes of memory | |
1651 | starting at @var{buffer}. For the @var{compiled} argument, supply the | |
1652 | same compiled regular expression structure that @code{regcomp} or | |
1653 | @code{regexec} was working with when it got the error. Alternatively, | |
1654 | you can supply @code{NULL} for @var{compiled}; you will still get a | |
1655 | meaningful error message, but it might not be as detailed. | |
1656 | ||
1657 | If the error message can't fit in @var{length} bytes (including a | |
1658 | terminating null character), then @code{regerror} truncates it. | |
1659 | The string that @code{regerror} stores is always null-terminated | |
1660 | even if it has been truncated. | |
1661 | ||
1662 | The return value of @code{regerror} is the minimum length needed to | |
1663 | store the entire error message. If this is less than @var{length}, then | |
1664 | the error message was not truncated, and you can use it. Otherwise, you | |
1665 | should call @code{regerror} again with a larger buffer. | |
1666 | ||
1667 | Here is a function which uses @code{regerror}, but always dynamically | |
1668 | allocates a buffer for the error message: | |
1669 | ||
1670 | @smallexample | |
1671 | char *get_regerror (int errcode, regex_t *compiled) | |
1672 | @{ | |
1673 | size_t length = regerror (errcode, compiled, NULL, 0); | |
1674 | char *buffer = xmalloc (length); | |
1675 | (void) regerror (errcode, compiled, buffer, length); | |
1676 | return buffer; | |
1677 | @} | |
1678 | @end smallexample | |
1679 | @end deftypefun | |
1680 | ||
28f540f4 RM |
1681 | @node Word Expansion |
1682 | @section Shell-Style Word Expansion | |
1683 | @cindex word expansion | |
1684 | @cindex expansion of shell words | |
1685 | ||
6d52618b | 1686 | @dfn{Word expansion} means the process of splitting a string into |
28f540f4 RM |
1687 | @dfn{words} and substituting for variables, commands, and wildcards |
1688 | just as the shell does. | |
1689 | ||
1690 | For example, when you write @samp{ls -l foo.c}, this string is split | |
1691 | into three separate words---@samp{ls}, @samp{-l} and @samp{foo.c}. | |
1692 | This is the most basic function of word expansion. | |
1693 | ||
1694 | When you write @samp{ls *.c}, this can become many words, because | |
1695 | the word @samp{*.c} can be replaced with any number of file names. | |
1696 | This is called @dfn{wildcard expansion}, and it is also a part of | |
1697 | word expansion. | |
1698 | ||
1699 | When you use @samp{echo $PATH} to print your path, you are taking | |
1700 | advantage of @dfn{variable substitution}, which is also part of word | |
1701 | expansion. | |
1702 | ||
1703 | Ordinary programs can perform word expansion just like the shell by | |
1704 | calling the library function @code{wordexp}. | |
1705 | ||
1706 | @menu | |
14eb5d5d UD |
1707 | * Expansion Stages:: What word expansion does to a string. |
1708 | * Calling Wordexp:: How to call @code{wordexp}. | |
1709 | * Flags for Wordexp:: Options you can enable in @code{wordexp}. | |
1710 | * Wordexp Example:: A sample program that does word expansion. | |
1711 | * Tilde Expansion:: Details of how tilde expansion works. | |
1712 | * Variable Substitution:: Different types of variable substitution. | |
28f540f4 RM |
1713 | @end menu |
1714 | ||
1715 | @node Expansion Stages | |
1716 | @subsection The Stages of Word Expansion | |
1717 | ||
1718 | When word expansion is applied to a sequence of words, it performs the | |
1719 | following transformations in the order shown here: | |
1720 | ||
1721 | @enumerate | |
1722 | @item | |
1723 | @cindex tilde expansion | |
1724 | @dfn{Tilde expansion}: Replacement of @samp{~foo} with the name of | |
1725 | the home directory of @samp{foo}. | |
1726 | ||
1727 | @item | |
1728 | Next, three different transformations are applied in the same step, | |
1729 | from left to right: | |
1730 | ||
1731 | @itemize @bullet | |
1732 | @item | |
1733 | @cindex variable substitution | |
1734 | @cindex substitution of variables and commands | |
1735 | @dfn{Variable substitution}: Environment variables are substituted for | |
1736 | references such as @samp{$foo}. | |
1737 | ||
1738 | @item | |
1739 | @cindex command substitution | |
1740 | @dfn{Command substitution}: Constructs such as @w{@samp{`cat foo`}} and | |
1741 | the equivalent @w{@samp{$(cat foo)}} are replaced with the output from | |
1742 | the inner command. | |
1743 | ||
1744 | @item | |
1745 | @cindex arithmetic expansion | |
1746 | @dfn{Arithmetic expansion}: Constructs such as @samp{$(($x-1))} are | |
1747 | replaced with the result of the arithmetic computation. | |
1748 | @end itemize | |
1749 | ||
1750 | @item | |
1751 | @cindex field splitting | |
1752 | @dfn{Field splitting}: subdivision of the text into @dfn{words}. | |
1753 | ||
1754 | @item | |
1755 | @cindex wildcard expansion | |
1756 | @dfn{Wildcard expansion}: The replacement of a construct such as @samp{*.c} | |
1757 | with a list of @samp{.c} file names. Wildcard expansion applies to an | |
1758 | entire word at a time, and replaces that word with 0 or more file names | |
1759 | that are themselves words. | |
1760 | ||
1761 | @item | |
1762 | @cindex quote removal | |
1763 | @cindex removal of quotes | |
1764 | @dfn{Quote removal}: The deletion of string-quotes, now that they have | |
1765 | done their job by inhibiting the above transformations when appropriate. | |
1766 | @end enumerate | |
1767 | ||
1768 | For the details of these transformations, and how to write the constructs | |
1769 | that use them, see @w{@cite{The BASH Manual}} (to appear). | |
1770 | ||
1771 | @node Calling Wordexp | |
1772 | @subsection Calling @code{wordexp} | |
1773 | ||
1774 | All the functions, constants and data types for word expansion are | |
1775 | declared in the header file @file{wordexp.h}. | |
1776 | ||
1777 | Word expansion produces a vector of words (strings). To return this | |
1778 | vector, @code{wordexp} uses a special data type, @code{wordexp_t}, which | |
1779 | is a structure. You pass @code{wordexp} the address of the structure, | |
1780 | and it fills in the structure's fields to tell you about the results. | |
1781 | ||
1782 | @comment wordexp.h | |
1783 | @comment POSIX.2 | |
1784 | @deftp {Data Type} {wordexp_t} | |
1785 | This data type holds a pointer to a word vector. More precisely, it | |
1786 | records both the address of the word vector and its size. | |
1787 | ||
1788 | @table @code | |
1789 | @item we_wordc | |
1790 | The number of elements in the vector. | |
1791 | ||
1792 | @item we_wordv | |
1793 | The address of the vector. This field has type @w{@code{char **}}. | |
1794 | ||
1795 | @item we_offs | |
1796 | The offset of the first real element of the vector, from its nominal | |
1797 | address in the @code{we_wordv} field. Unlike the other fields, this | |
1798 | is always an input to @code{wordexp}, rather than an output from it. | |
1799 | ||
1800 | If you use a nonzero offset, then that many elements at the beginning of | |
1801 | the vector are left empty. (The @code{wordexp} function fills them with | |
1802 | null pointers.) | |
1803 | ||
1804 | The @code{we_offs} field is meaningful only if you use the | |
1805 | @code{WRDE_DOOFFS} flag. Otherwise, the offset is always zero | |
1806 | regardless of what is in this field, and the first real element comes at | |
1807 | the beginning of the vector. | |
1808 | @end table | |
1809 | @end deftp | |
1810 | ||
1811 | @comment wordexp.h | |
1812 | @comment POSIX.2 | |
1813 | @deftypefun int wordexp (const char *@var{words}, wordexp_t *@var{word-vector-ptr}, int @var{flags}) | |
03483ada AO |
1814 | @safety{@prelim{}@mtunsafe{@mtasurace{:utent} @mtasuconst{:@mtsenv{}} @mtsenv{} @mtascusig{:ALRM} @mtascutimer{} @mtslocale{}}@asunsafe{@ascudlopen{} @ascuplugin{} @ascuintl{} @ascuheap{} @asucorrupt{} @asulock{}}@acunsafe{@acucorrupt{} @aculock{} @acsfd{} @acsmem{}}} |
1815 | @c wordexp @mtasurace:utent @mtasuconst:@mtsenv @mtsenv @mtascusig:ALRM @mtascutimer @mtslocale @ascudlopen @ascuplugin @ascuintl @ascuheap @asucorrupt @asulock @acucorrupt @aculock @acsfd @acsmem | |
1816 | @c w_newword ok | |
1817 | @c wordfree dup @asucorrupt @ascuheap @acucorrupt @acsmem | |
1818 | @c calloc dup @ascuheap @acsmem | |
1819 | @c getenv dup @mtsenv | |
1820 | @c strcpy dup ok | |
1821 | @c parse_backslash @ascuheap @acsmem | |
1822 | @c w_addchar dup @ascuheap @acsmem | |
1823 | @c parse_dollars @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1824 | @c w_addchar dup @ascuheap @acsmem | |
1825 | @c parse_arith @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1826 | @c w_newword dup ok | |
1827 | @c parse_dollars dup @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1828 | @c parse_backtick dup @ascuplugin @ascuheap @aculock @acsfd @acsmem | |
1829 | @c parse_qtd_backslash dup @ascuheap @acsmem | |
1830 | @c eval_expr @mtslocale | |
1831 | @c eval_expr_multidiv @mtslocale | |
1832 | @c eval_expr_val @mtslocale | |
1833 | @c isspace dup @mtslocale | |
1834 | @c eval_expr dup @mtslocale | |
1835 | @c isspace dup @mtslocale | |
1836 | @c isspace dup @mtslocale | |
1837 | @c free dup @ascuheap @acsmem | |
1838 | @c w_addchar dup @ascuheap @acsmem | |
1839 | @c w_addstr dup @ascuheap @acsmem | |
1840 | @c itoa_word dup ok | |
1841 | @c parse_comm @ascuplugin @ascuheap @aculock @acsfd @acsmem | |
1842 | @c w_newword dup ok | |
1843 | @c pthread_setcancelstate @ascuplugin @ascuheap @acsmem | |
1844 | @c (disable cancellation around exec_comm; it may do_cancel the | |
1845 | @c second time, if async cancel is enabled) | |
1846 | @c THREAD_ATOMIC_CMPXCHG_VAL dup ok | |
1847 | @c CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS dup ok | |
1848 | @c do_cancel @ascuplugin @ascuheap @acsmem | |
1849 | @c THREAD_ATOMIC_BIT_SET dup ok | |
1850 | @c pthread_unwind @ascuplugin @ascuheap @acsmem | |
1851 | @c Unwind_ForcedUnwind if available @ascuplugin @ascuheap @acsmem | |
1852 | @c libc_unwind_longjmp otherwise | |
1853 | @c cleanups | |
1854 | @c exec_comm @ascuplugin @ascuheap @aculock @acsfd @acsmem | |
1855 | @c pipe2 dup ok | |
1856 | @c pipe dup ok | |
1857 | @c fork dup @ascuplugin @aculock | |
1858 | @c close dup @acsfd | |
1859 | @c on child: exec_comm_child -> exec or abort | |
1860 | @c waitpid dup ok | |
1861 | @c read dup ok | |
1862 | @c w_addmem dup @ascuheap @acsmem | |
1863 | @c strchr dup ok | |
1864 | @c w_addword dup @ascuheap @acsmem | |
1865 | @c w_newword dup ok | |
1866 | @c w_addchar dup @ascuheap @acsmem | |
1867 | @c free dup @ascuheap @acsmem | |
1868 | @c kill dup ok | |
1869 | @c free dup @ascuheap @acsmem | |
1870 | @c parse_param @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1871 | @c reads from __libc_argc and __libc_argv without guards | |
1872 | @c w_newword dup ok | |
1873 | @c isalpha dup @mtslocale^^ | |
1874 | @c w_addchar dup @ascuheap @acsmem | |
1875 | @c isalnum dup @mtslocale^^ | |
1876 | @c isdigit dup @mtslocale^^ | |
1877 | @c strchr dup ok | |
1878 | @c itoa_word dup ok | |
1879 | @c atoi dup @mtslocale | |
1880 | @c getpid dup ok | |
1881 | @c w_addstr dup @ascuheap @acsmem | |
1882 | @c free dup @ascuheap @acsmem | |
1883 | @c strlen dup ok | |
1884 | @c malloc dup @ascuheap @acsmem | |
1885 | @c stpcpy dup ok | |
1886 | @c w_addword dup @ascuheap @acsmem | |
1887 | @c strdup dup @ascuheap @acsmem | |
1888 | @c getenv dup @mtsenv | |
1889 | @c parse_dollars dup @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1890 | @c parse_tilde dup @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1891 | @c fnmatch dup @mtsenv @mtslocale @ascuheap @acsmem | |
1892 | @c mempcpy dup ok | |
1893 | @c _ dup @ascuintl | |
1894 | @c fxprintf dup @aculock | |
1895 | @c setenv dup @mtasuconst:@mtsenv @ascuheap @asulock @acucorrupt @aculock @acsmem | |
1896 | @c strspn dup ok | |
1897 | @c strcspn dup ok | |
1898 | @c parse_backtick @ascuplugin @ascuheap @aculock @acsfd @acsmem | |
1899 | @c w_newword dup ok | |
1900 | @c exec_comm dup @ascuplugin @ascuheap @aculock @acsfd @acsmem | |
1901 | @c free dup @ascuheap @acsmem | |
1902 | @c parse_qtd_backslash dup @ascuheap @acsmem | |
1903 | @c parse_backslash dup @ascuheap @acsmem | |
1904 | @c w_addchar dup @ascuheap @acsmem | |
1905 | @c parse_dquote @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1906 | @c parse_dollars dup @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1907 | @c parse_backtick dup @ascuplugin @ascuheap @aculock @acsfd @acsmem | |
1908 | @c parse_qtd_backslash dup @ascuheap @acsmem | |
1909 | @c w_addchar dup @ascuheap @acsmem | |
1910 | @c w_addword dup @ascuheap @acsmem | |
1911 | @c strdup dup @ascuheap @acsmem | |
1912 | @c realloc dup @ascuheap @acsmem | |
1913 | @c free dup @ascuheap @acsmem | |
1914 | @c parse_squote dup @ascuheap @acsmem | |
1915 | @c w_addchar dup @ascuheap @acsmem | |
1916 | @c parse_tilde @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1917 | @c strchr dup ok | |
1918 | @c w_addchar dup @ascuheap @acsmem | |
1919 | @c getenv dup @mtsenv | |
1920 | @c w_addstr dup @ascuheap @acsmem | |
1921 | @c strlen dup ok | |
1922 | @c w_addmem dup @ascuheap @acsmem | |
1923 | @c realloc dup @ascuheap @acsmem | |
1924 | @c free dup @ascuheap @acsmem | |
1925 | @c mempcpy dup ok | |
1926 | @c getuid dup ok | |
1927 | @c getpwuid_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1928 | @c getpwnam_r dup @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1929 | @c parse_glob @mtasurace:utent @mtasuconst:@mtsenv @mtsenv @mtascusig:ALRM @mtascutimer @mtslocale @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1930 | @c strchr dup ok | |
1931 | @c parse_dollars dup @mtasuconst:@mtsenv @mtslocale @mtsenv @ascudlopen @ascuplugin @ascuintl @ascuheap @asulock @acucorrupt @aculock @acsfd @acsmem | |
1932 | @c parse_qtd_backslash @ascuheap @acsmem | |
1933 | @c w_addchar dup @ascuheap @acsmem | |
1934 | @c parse_backslash dup @ascuheap @acsmem | |
1935 | @c w_addchar dup @ascuheap @acsmem | |
1936 | @c w_addword dup @ascuheap @acsmem | |
1937 | @c w_newword dup ok | |
1938 | @c do_parse_glob @mtasurace:utent @mtsenv @mtascusig:ALRM @mtascutimer @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @aculock @acsfd @acsmem | |
1939 | @c glob dup @mtasurace:utent @mtsenv @mtascusig:ALRM @mtascutimer @mtslocale @ascudlopen @ascuplugin @ascuheap @asulock @aculock @acsfd @acsmem [auto glob_t avoids @asucorrupt @acucorrupt] | |
1940 | @c w_addstr dup @ascuheap @acsmem | |
1941 | @c w_addchar dup @ascuheap @acsmem | |
1942 | @c globfree dup @ascuheap @acsmem [auto glob_t avoids @asucorrupt @acucorrupt] | |
1943 | @c free dup @ascuheap @acsmem | |
1944 | @c w_newword dup ok | |
1945 | @c strdup dup @ascuheap @acsmem | |
1946 | @c w_addword dup @ascuheap @acsmem | |
1947 | @c wordfree dup @asucorrupt @ascuheap @acucorrupt @acsmem | |
1948 | @c strchr dup ok | |
1949 | @c w_addchar dup @ascuheap @acsmem | |
1950 | @c realloc dup @ascuheap @acsmem | |
1951 | @c free dup @ascuheap @acsmem | |
1952 | @c free dup @ascuheap @acsmem | |
28f540f4 RM |
1953 | Perform word expansion on the string @var{words}, putting the result in |
1954 | a newly allocated vector, and store the size and address of this vector | |
1955 | into @code{*@var{word-vector-ptr}}. The argument @var{flags} is a | |
1956 | combination of bit flags; see @ref{Flags for Wordexp}, for details of | |
1957 | the flags. | |
1958 | ||
1959 | You shouldn't use any of the characters @samp{|&;<>} in the string | |
1960 | @var{words} unless they are quoted; likewise for newline. If you use | |
1961 | these characters unquoted, you will get the @code{WRDE_BADCHAR} error | |
1962 | code. Don't use parentheses or braces unless they are quoted or part of | |
1963 | a word expansion construct. If you use quotation characters @samp{'"`}, | |
1964 | they should come in pairs that balance. | |
1965 | ||
1966 | The results of word expansion are a sequence of words. The function | |
1967 | @code{wordexp} allocates a string for each resulting word, then | |
1968 | allocates a vector of type @code{char **} to store the addresses of | |
1969 | these strings. The last element of the vector is a null pointer. | |
1970 | This vector is called the @dfn{word vector}. | |
1971 | ||
1972 | To return this vector, @code{wordexp} stores both its address and its | |
1973 | length (number of elements, not counting the terminating null pointer) | |
1974 | into @code{*@var{word-vector-ptr}}. | |
1975 | ||
1976 | If @code{wordexp} succeeds, it returns 0. Otherwise, it returns one | |
1977 | of these error codes: | |
1978 | ||
1979 | @table @code | |
1980 | @comment wordexp.h | |
1981 | @comment POSIX.2 | |
1982 | @item WRDE_BADCHAR | |
1983 | The input string @var{words} contains an unquoted invalid character such | |
1984 | as @samp{|}. | |
1985 | ||
1986 | @comment wordexp.h | |
1987 | @comment POSIX.2 | |
1988 | @item WRDE_BADVAL | |
1989 | The input string refers to an undefined shell variable, and you used the flag | |
1990 | @code{WRDE_UNDEF} to forbid such references. | |
1991 | ||
1992 | @comment wordexp.h | |
1993 | @comment POSIX.2 | |
1994 | @item WRDE_CMDSUB | |
1995 | The input string uses command substitution, and you used the flag | |
1996 | @code{WRDE_NOCMD} to forbid command substitution. | |
1997 | ||
1998 | @comment wordexp.h | |
1999 | @comment POSIX.2 | |
2000 | @item WRDE_NOSPACE | |
2001 | It was impossible to allocate memory to hold the result. In this case, | |
2002 | @code{wordexp} can store part of the results---as much as it could | |
2003 | allocate room for. | |
2004 | ||
2005 | @comment wordexp.h | |
2006 | @comment POSIX.2 | |
2007 | @item WRDE_SYNTAX | |
2008 | There was a syntax error in the input string. For example, an unmatched | |
2b028564 FW |
2009 | quoting character is a syntax error. This error code is also used to |
2010 | signal division by zero and overflow in arithmetic expansion. | |
28f540f4 RM |
2011 | @end table |
2012 | @end deftypefun | |
2013 | ||
2014 | @comment wordexp.h | |
2015 | @comment POSIX.2 | |
2016 | @deftypefun void wordfree (wordexp_t *@var{word-vector-ptr}) | |
03483ada AO |
2017 | @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}} |
2018 | @c wordfree dup @asucorrupt @ascuheap @acucorrupt @acsmem | |
2019 | @c free dup @ascuheap @acsmem | |
28f540f4 RM |
2020 | Free the storage used for the word-strings and vector that |
2021 | @code{*@var{word-vector-ptr}} points to. This does not free the | |
2022 | structure @code{*@var{word-vector-ptr}} itself---only the other | |
2023 | data it points to. | |
2024 | @end deftypefun | |
2025 | ||
2026 | @node Flags for Wordexp | |
2027 | @subsection Flags for Word Expansion | |
2028 | ||
6d52618b | 2029 | This section describes the flags that you can specify in the |
28f540f4 RM |
2030 | @var{flags} argument to @code{wordexp}. Choose the flags you want, |
2031 | and combine them with the C operator @code{|}. | |
2032 | ||
2033 | @table @code | |
2034 | @comment wordexp.h | |
2035 | @comment POSIX.2 | |
2036 | @item WRDE_APPEND | |
2037 | Append the words from this expansion to the vector of words produced by | |
2038 | previous calls to @code{wordexp}. This way you can effectively expand | |
2039 | several words as if they were concatenated with spaces between them. | |
2040 | ||
2041 | In order for appending to work, you must not modify the contents of the | |
2042 | word vector structure between calls to @code{wordexp}. And, if you set | |
2043 | @code{WRDE_DOOFFS} in the first call to @code{wordexp}, you must also | |
2044 | set it when you append to the results. | |
2045 | ||
2046 | @comment wordexp.h | |
2047 | @comment POSIX.2 | |
2048 | @item WRDE_DOOFFS | |
2049 | Leave blank slots at the beginning of the vector of words. | |
2050 | The @code{we_offs} field says how many slots to leave. | |
2051 | The blank slots contain null pointers. | |
2052 | ||
2053 | @comment wordexp.h | |
2054 | @comment POSIX.2 | |
2055 | @item WRDE_NOCMD | |
2056 | Don't do command substitution; if the input requests command substitution, | |
2057 | report an error. | |
2058 | ||
2059 | @comment wordexp.h | |
2060 | @comment POSIX.2 | |
2061 | @item WRDE_REUSE | |
2062 | Reuse a word vector made by a previous call to @code{wordexp}. | |
2063 | Instead of allocating a new vector of words, this call to @code{wordexp} | |
2064 | will use the vector that already exists (making it larger if necessary). | |
2065 | ||
2066 | Note that the vector may move, so it is not safe to save an old pointer | |
2067 | and use it again after calling @code{wordexp}. You must fetch | |
2068 | @code{we_pathv} anew after each call. | |
2069 | ||
2070 | @comment wordexp.h | |
2071 | @comment POSIX.2 | |
2072 | @item WRDE_SHOWERR | |
2073 | Do show any error messages printed by commands run by command substitution. | |
2074 | More precisely, allow these commands to inherit the standard error output | |
2075 | stream of the current process. By default, @code{wordexp} gives these | |
2076 | commands a standard error stream that discards all output. | |
2077 | ||
2078 | @comment wordexp.h | |
2079 | @comment POSIX.2 | |
2080 | @item WRDE_UNDEF | |
2081 | If the input refers to a shell variable that is not defined, report an | |
2082 | error. | |
2083 | @end table | |
2084 | ||
2085 | @node Wordexp Example | |
2086 | @subsection @code{wordexp} Example | |
2087 | ||
2088 | Here is an example of using @code{wordexp} to expand several strings | |
2089 | and use the results to run a shell command. It also shows the use of | |
2090 | @code{WRDE_APPEND} to concatenate the expansions and of @code{wordfree} | |
2091 | to free the space allocated by @code{wordexp}. | |
2092 | ||
2093 | @smallexample | |
2094 | int | |
1daa8164 | 2095 | expand_and_execute (const char *program, const char **options) |
28f540f4 RM |
2096 | @{ |
2097 | wordexp_t result; | |
2098 | pid_t pid | |
2099 | int status, i; | |
2100 | ||
2101 | /* @r{Expand the string for the program to run.} */ | |
2102 | switch (wordexp (program, &result, 0)) | |
2103 | @{ | |
2104 | case 0: /* @r{Successful}. */ | |
2105 | break; | |
2106 | case WRDE_NOSPACE: | |
2107 | /* @r{If the error was @code{WRDE_NOSPACE},} | |
2108 | @r{then perhaps part of the result was allocated.} */ | |
2109 | wordfree (&result); | |
2110 | default: /* @r{Some other error.} */ | |
2111 | return -1; | |
2112 | @} | |
2113 | ||
2114 | /* @r{Expand the strings specified for the arguments.} */ | |
1daa8164 | 2115 | for (i = 0; options[i] != NULL; i++) |
28f540f4 | 2116 | @{ |
1daa8164 | 2117 | if (wordexp (options[i], &result, WRDE_APPEND)) |
28f540f4 RM |
2118 | @{ |
2119 | wordfree (&result); | |
2120 | return -1; | |
2121 | @} | |
2122 | @} | |
2123 | ||
2124 | pid = fork (); | |
2125 | if (pid == 0) | |
2126 | @{ | |
2127 | /* @r{This is the child process. Execute the command.} */ | |
2128 | execv (result.we_wordv[0], result.we_wordv); | |
2129 | exit (EXIT_FAILURE); | |
2130 | @} | |
2131 | else if (pid < 0) | |
2132 | /* @r{The fork failed. Report failure.} */ | |
2133 | status = -1; | |
2134 | else | |
2135 | /* @r{This is the parent process. Wait for the child to complete.} */ | |
2136 | if (waitpid (pid, &status, 0) != pid) | |
2137 | status = -1; | |
2138 | ||
2139 | wordfree (&result); | |
2140 | return status; | |
2141 | @} | |
2142 | @end smallexample | |
2143 | ||
28f540f4 RM |
2144 | @node Tilde Expansion |
2145 | @subsection Details of Tilde Expansion | |
2146 | ||
2147 | It's a standard part of shell syntax that you can use @samp{~} at the | |
2148 | beginning of a file name to stand for your own home directory. You | |
2149 | can use @samp{~@var{user}} to stand for @var{user}'s home directory. | |
2150 | ||
2151 | @dfn{Tilde expansion} is the process of converting these abbreviations | |
2152 | to the directory names that they stand for. | |
2153 | ||
2154 | Tilde expansion applies to the @samp{~} plus all following characters up | |
2155 | to whitespace or a slash. It takes place only at the beginning of a | |
2156 | word, and only if none of the characters to be transformed is quoted in | |
2157 | any way. | |
2158 | ||
2159 | Plain @samp{~} uses the value of the environment variable @code{HOME} | |
2160 | as the proper home directory name. @samp{~} followed by a user name | |
2161 | uses @code{getpwname} to look up that user in the user database, and | |
2162 | uses whatever directory is recorded there. Thus, @samp{~} followed | |
2163 | by your own name can give different results from plain @samp{~}, if | |
2164 | the value of @code{HOME} is not really your home directory. | |
2165 | ||
2166 | @node Variable Substitution | |
2167 | @subsection Details of Variable Substitution | |
2168 | ||
2169 | Part of ordinary shell syntax is the use of @samp{$@var{variable}} to | |
2170 | substitute the value of a shell variable into a command. This is called | |
2171 | @dfn{variable substitution}, and it is one part of doing word expansion. | |
2172 | ||
2173 | There are two basic ways you can write a variable reference for | |
2174 | substitution: | |
2175 | ||
2176 | @table @code | |
2177 | @item $@{@var{variable}@} | |
2178 | If you write braces around the variable name, then it is completely | |
2179 | unambiguous where the variable name ends. You can concatenate | |
2180 | additional letters onto the end of the variable value by writing them | |
2181 | immediately after the close brace. For example, @samp{$@{foo@}s} | |
2182 | expands into @samp{tractors}. | |
2183 | ||
2184 | @item $@var{variable} | |
2185 | If you do not put braces around the variable name, then the variable | |
2186 | name consists of all the alphanumeric characters and underscores that | |
2187 | follow the @samp{$}. The next punctuation character ends the variable | |
2188 | name. Thus, @samp{$foo-bar} refers to the variable @code{foo} and expands | |
2189 | into @samp{tractor-bar}. | |
2190 | @end table | |
2191 | ||
2192 | When you use braces, you can also use various constructs to modify the | |
2193 | value that is substituted, or test it in various ways. | |
2194 | ||
2195 | @table @code | |
2196 | @item $@{@var{variable}:-@var{default}@} | |
2197 | Substitute the value of @var{variable}, but if that is empty or | |
2198 | undefined, use @var{default} instead. | |
2199 | ||
2200 | @item $@{@var{variable}:=@var{default}@} | |
2201 | Substitute the value of @var{variable}, but if that is empty or | |
2202 | undefined, use @var{default} instead and set the variable to | |
2203 | @var{default}. | |
2204 | ||
2205 | @item $@{@var{variable}:?@var{message}@} | |
2206 | If @var{variable} is defined and not empty, substitute its value. | |
2207 | ||
2208 | Otherwise, print @var{message} as an error message on the standard error | |
2209 | stream, and consider word expansion a failure. | |
2210 | ||
2211 | @c ??? How does wordexp report such an error? | |
14eb5d5d | 2212 | @c WRDE_BADVAL is returned. |
28f540f4 RM |
2213 | |
2214 | @item $@{@var{variable}:+@var{replacement}@} | |
2215 | Substitute @var{replacement}, but only if @var{variable} is defined and | |
2216 | nonempty. Otherwise, substitute nothing for this construct. | |
2217 | @end table | |
2218 | ||
2219 | @table @code | |
2220 | @item $@{#@var{variable}@} | |
2221 | Substitute a numeral which expresses in base ten the number of | |
2222 | characters in the value of @var{variable}. @samp{$@{#foo@}} stands for | |
2223 | @samp{7}, because @samp{tractor} is seven characters. | |
2224 | @end table | |
2225 | ||
2226 | These variants of variable substitution let you remove part of the | |
6d52618b | 2227 | variable's value before substituting it. The @var{prefix} and |
28f540f4 RM |
2228 | @var{suffix} are not mere strings; they are wildcard patterns, just |
2229 | like the patterns that you use to match multiple file names. But | |
2230 | in this context, they match against parts of the variable value | |
2231 | rather than against file names. | |
2232 | ||
2233 | @table @code | |
2234 | @item $@{@var{variable}%%@var{suffix}@} | |
2235 | Substitute the value of @var{variable}, but first discard from that | |
2236 | variable any portion at the end that matches the pattern @var{suffix}. | |
2237 | ||
2238 | If there is more than one alternative for how to match against | |
2239 | @var{suffix}, this construct uses the longest possible match. | |
2240 | ||
2241 | Thus, @samp{$@{foo%%r*@}} substitutes @samp{t}, because the largest | |
2242 | match for @samp{r*} at the end of @samp{tractor} is @samp{ractor}. | |
2243 | ||
2244 | @item $@{@var{variable}%@var{suffix}@} | |
2245 | Substitute the value of @var{variable}, but first discard from that | |
2246 | variable any portion at the end that matches the pattern @var{suffix}. | |
2247 | ||
2248 | If there is more than one alternative for how to match against | |
2249 | @var{suffix}, this construct uses the shortest possible alternative. | |
2250 | ||
d6b3602f | 2251 | Thus, @samp{$@{foo%r*@}} substitutes @samp{tracto}, because the shortest |
28f540f4 RM |
2252 | match for @samp{r*} at the end of @samp{tractor} is just @samp{r}. |
2253 | ||
2254 | @item $@{@var{variable}##@var{prefix}@} | |
2255 | Substitute the value of @var{variable}, but first discard from that | |
2256 | variable any portion at the beginning that matches the pattern @var{prefix}. | |
2257 | ||
2258 | If there is more than one alternative for how to match against | |
2259 | @var{prefix}, this construct uses the longest possible match. | |
2260 | ||
d6b3602f RM |
2261 | Thus, @samp{$@{foo##*t@}} substitutes @samp{or}, because the largest |
2262 | match for @samp{*t} at the beginning of @samp{tractor} is @samp{tract}. | |
28f540f4 RM |
2263 | |
2264 | @item $@{@var{variable}#@var{prefix}@} | |
2265 | Substitute the value of @var{variable}, but first discard from that | |
2266 | variable any portion at the beginning that matches the pattern @var{prefix}. | |
2267 | ||
2268 | If there is more than one alternative for how to match against | |
2269 | @var{prefix}, this construct uses the shortest possible alternative. | |
2270 | ||
d6b3602f RM |
2271 | Thus, @samp{$@{foo#*t@}} substitutes @samp{ractor}, because the shortest |
2272 | match for @samp{*t} at the beginning of @samp{tractor} is just @samp{t}. | |
28f540f4 | 2273 | |
14eb5d5d | 2274 | @end table |