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fea681da | 1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
c6ec3685 MK |
2 | .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
fea681da | 4 | .\" |
93015253 | 5 | .\" %%%LICENSE_START(VERBATIM) |
fea681da MK |
6 | .\" Permission is granted to make and distribute verbatim copies of this |
7 | .\" manual provided the copyright notice and this permission notice are | |
8 | .\" preserved on all copies. | |
9 | .\" | |
10 | .\" Permission is granted to copy and distribute modified versions of this | |
11 | .\" manual under the conditions for verbatim copying, provided that the | |
12 | .\" entire resulting derived work is distributed under the terms of a | |
13 | .\" permission notice identical to this one. | |
c13182ef | 14 | .\" |
fea681da MK |
15 | .\" Since the Linux kernel and libraries are constantly changing, this |
16 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
17 | .\" responsibility for errors or omissions, or for damages resulting from | |
18 | .\" the use of the information contained herein. The author(s) may not | |
19 | .\" have taken the same level of care in the production of this manual, | |
20 | .\" which is licensed free of charge, as they might when working | |
21 | .\" professionally. | |
c13182ef | 22 | .\" |
fea681da MK |
23 | .\" Formatted or processed versions of this manual, if unaccompanied by |
24 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 25 | .\" %%%LICENSE_END |
fea681da MK |
26 | .\" |
27 | .\" References consulted: | |
28 | .\" Linux libc source code | |
6b2fc294 | 29 | .\" Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991) |
fea681da MK |
30 | .\" 386BSD man pages |
31 | .\" | |
32 | .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) | |
33 | .\" Modified 1996-05-27 by Martin Schulze (joey@linux.de) | |
34 | .\" Modified 2003-11-15 by aeb | |
c6ec3685 | 35 | .\" 2008-11-07, mtk, Added an example program for getpwnam_r(). |
fea681da | 36 | .\" |
4b8c67d9 | 37 | .TH GETPWNAM 3 2017-09-15 "GNU" "Linux Programmer's Manual" |
fea681da MK |
38 | .SH NAME |
39 | getpwnam, getpwnam_r, getpwuid, getpwuid_r \- get password file entry | |
40 | .SH SYNOPSIS | |
41 | .nf | |
42 | .B #include <sys/types.h> | |
43 | .B #include <pwd.h> | |
68e4db0a | 44 | .PP |
fea681da | 45 | .BI "struct passwd *getpwnam(const char *" name ); |
68e4db0a | 46 | .PP |
fea681da | 47 | .BI "struct passwd *getpwuid(uid_t " uid ); |
68e4db0a | 48 | .PP |
3adc12e9 | 49 | .BI "int getpwnam_r(const char *" name ", struct passwd *" pwd , |
ae577310 | 50 | .BI " char *" buf ", size_t " buflen ", struct passwd **" result ); |
68e4db0a | 51 | .PP |
3adc12e9 | 52 | .BI "int getpwuid_r(uid_t " uid ", struct passwd *" pwd , |
ae577310 | 53 | .BI " char *" buf ", size_t " buflen ", struct passwd **" result ); |
fea681da | 54 | .fi |
68e4db0a | 55 | .PP |
cc4615cc MK |
56 | .in -4n |
57 | Feature Test Macro Requirements for glibc (see | |
58 | .BR feature_test_macros (7)): | |
59 | .in | |
68e4db0a | 60 | .PP |
cc4615cc MK |
61 | .ad l |
62 | .BR getpwnam_r (), | |
63 | .BR getpwuid_r (): | |
f496f649 | 64 | .RS 4 |
9db90c7c MK |
65 | _POSIX_C_SOURCE |
66 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE | |
f496f649 | 67 | .RE |
cc4615cc | 68 | .ad b |
fea681da MK |
69 | .SH DESCRIPTION |
70 | The | |
63aa9df0 | 71 | .BR getpwnam () |
fea681da | 72 | function returns a pointer to a structure containing |
f936cf26 | 73 | the broken-out fields of the record in the password database |
c13182ef | 74 | (e.g., the local password file |
f2738b39 MK |
75 | .IR /etc/passwd , |
76 | NIS, and LDAP) | |
18701562 | 77 | that matches the username |
fea681da MK |
78 | .IR name . |
79 | .PP | |
80 | The | |
63aa9df0 | 81 | .BR getpwuid () |
fea681da | 82 | function returns a pointer to a structure containing |
f2738b39 | 83 | the broken-out fields of the record in the password database |
f936cf26 | 84 | that matches the user ID |
fea681da MK |
85 | .IR uid . |
86 | .PP | |
fea681da | 87 | The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows: |
51f5698d | 88 | .PP |
bd191423 | 89 | .in +4n |
b8302363 | 90 | .EX |
fea681da | 91 | struct passwd { |
18701562 | 92 | char *pw_name; /* username */ |
f2738b39 | 93 | char *pw_passwd; /* user password */ |
34c97781 MK |
94 | uid_t pw_uid; /* user ID */ |
95 | gid_t pw_gid; /* group ID */ | |
958680cd | 96 | char *pw_gecos; /* user information */ |
f2738b39 MK |
97 | char *pw_dir; /* home directory */ |
98 | char *pw_shell; /* shell program */ | |
fea681da | 99 | }; |
b8302363 | 100 | .EE |
bd191423 | 101 | .in |
fea681da | 102 | .PP |
011520b8 MK |
103 | See |
104 | .BR passwd (5) | |
105 | for more information about these fields. | |
106 | .PP | |
107 | The | |
108 | .BR getpwnam_r () | |
109 | and | |
110 | .BR getpwuid_r () | |
111 | functions obtain the same information as | |
112 | .BR getpwnam () | |
113 | and | |
114 | .BR getpwuid (), | |
115 | but store the retrieved | |
116 | .I passwd | |
117 | structure in the space pointed to by | |
118 | .IR pwd . | |
119 | The string fields pointed to by the members of the | |
120 | .I passwd | |
121 | structure are stored in the buffer | |
122 | .I buf | |
123 | of size | |
124 | .IR buflen . | |
125 | A pointer to the result (in case of success) or NULL (in case no entry | |
126 | was found or an error occurred) is stored in | |
127 | .IR *result . | |
128 | .PP | |
f6dc3611 | 129 | The call |
847e0d88 | 130 | .PP |
f6dc3611 | 131 | sysconf(_SC_GETPW_R_SIZE_MAX) |
847e0d88 | 132 | .PP |
f6dc3611 MK |
133 | returns either \-1, without changing |
134 | .IR errno , | |
135 | or an initial suggested size for | |
136 | .IR buf . | |
137 | (If this size is too small, | |
138 | the call fails with | |
139 | .BR ERANGE , | |
140 | in which case the caller can retry with a larger buffer.) | |
47297adb | 141 | .SH RETURN VALUE |
60a90ecd MK |
142 | The |
143 | .BR getpwnam () | |
144 | and | |
145 | .BR getpwuid () | |
146 | functions return a pointer to a | |
f2738b39 MK |
147 | .I passwd |
148 | structure, or NULL if the matching entry is not found or | |
149 | an error occurs. | |
150 | If an error occurs, | |
fea681da | 151 | .I errno |
f2738b39 MK |
152 | is set appropriately. |
153 | If one wants to check | |
fea681da MK |
154 | .I errno |
155 | after the call, it should be set to zero before the call. | |
dd3568a1 | 156 | .PP |
57c1b002 | 157 | The return value may point to a static area, and may be overwritten |
fea681da | 158 | by subsequent calls to |
3a72373c | 159 | .BR getpwent (3), |
63aa9df0 | 160 | .BR getpwnam (), |
fea681da | 161 | or |
63aa9df0 | 162 | .BR getpwuid (). |
48e4cfa0 MK |
163 | (Do not pass the returned pointer to |
164 | .BR free (3).) | |
dd3568a1 | 165 | .PP |
bbab485d | 166 | On success, |
60a90ecd MK |
167 | .BR getpwnam_r () |
168 | and | |
169 | .BR getpwuid_r () | |
bbab485d | 170 | return zero, and set |
3adc12e9 | 171 | .IR *result |
bbab485d | 172 | to |
3adc12e9 | 173 | .IR pwd . |
bbab485d MK |
174 | If no matching password record was found, |
175 | these functions return 0 and store NULL in | |
3adc12e9 | 176 | .IR *result . |
bbab485d | 177 | In case of error, an error number is returned, and NULL is stored in |
3adc12e9 | 178 | .IR *result . |
fea681da MK |
179 | .SH ERRORS |
180 | .TP | |
181 | .BR 0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ... " | |
182 | The given | |
183 | .I name | |
184 | or | |
185 | .I uid | |
186 | was not found. | |
187 | .TP | |
188 | .B EINTR | |
bb14af39 MK |
189 | A signal was caught; see |
190 | .BR signal (7). | |
fea681da MK |
191 | .TP |
192 | .B EIO | |
193 | I/O error. | |
194 | .TP | |
195 | .B EMFILE | |
26c32fab | 196 | The per-process limit on the number of open file descriptors has been reached. |
fea681da MK |
197 | .TP |
198 | .B ENFILE | |
e258766b | 199 | The system-wide limit on the total number of open files has been reached. |
fea681da MK |
200 | .TP |
201 | .B ENOMEM | |
f2738b39 | 202 | .\" not in POSIX |
b2133414 MK |
203 | Insufficient memory to allocate |
204 | .I passwd | |
205 | structure. | |
fea681da MK |
206 | .\" This structure is static, allocated 0 or 1 times. No memory leak. (libc45) |
207 | .TP | |
208 | .B ERANGE | |
209 | Insufficient buffer space supplied. | |
210 | .SH FILES | |
211 | .TP | |
212 | .I /etc/passwd | |
f2738b39 | 213 | local password database file |
404197c7 | 214 | .SH ATTRIBUTES |
2973863a MK |
215 | For an explanation of the terms used in this section, see |
216 | .BR attributes (7). | |
217 | .TS | |
218 | allbox; | |
693e6cf5 | 219 | lb lb lb |
2973863a MK |
220 | l l l. |
221 | Interface Attribute Value | |
222 | T{ | |
693e6cf5 MS |
223 | .BR getpwnam () |
224 | T} Thread safety MT-Unsafe race:pwnam locale | |
225 | T{ | |
404197c7 | 226 | .BR getpwuid () |
693e6cf5 | 227 | T} Thread safety MT-Unsafe race:pwuid locale |
2973863a MK |
228 | T{ |
229 | .BR getpwnam_r (), | |
693e6cf5 | 230 | .br |
404197c7 | 231 | .BR getpwuid_r () |
693e6cf5 | 232 | T} Thread safety MT-Safe locale |
2973863a | 233 | .TE |
47297adb | 234 | .SH CONFORMING TO |
9720f05e | 235 | POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD. |
958680cd MK |
236 | The |
237 | .I pw_gecos | |
238 | field is not specified in POSIX, but is present on most implementations. | |
fea681da | 239 | .SH NOTES |
68e1685c | 240 | The formulation given above under "RETURN VALUE" is from POSIX.1-2001. |
6b2fc294 | 241 | It does not call "not found" an error, and hence does not specify what value |
fea681da | 242 | .I errno |
c13182ef MK |
243 | might have in this situation. |
244 | But that makes it impossible to recognize | |
245 | errors. | |
246 | One might argue that according to POSIX | |
fea681da | 247 | .I errno |
c13182ef MK |
248 | should be left unchanged if an entry is not found. |
249 | Experiments on various | |
008f1ecc | 250 | UNIX-like systems show that lots of different values occur in this |
a797afac | 251 | situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM, and probably others. |
fea681da MK |
252 | .\" more precisely: |
253 | .\" AIX 5.1 - gives ESRCH | |
254 | .\" OSF1 4.0g - gives EWOULDBLOCK | |
db85058b MK |
255 | .\" libc, glibc up to version 2.6, Irix 6.5 - give ENOENT |
256 | .\" glibc since version 2.7 - give 0 | |
fea681da MK |
257 | .\" FreeBSD 4.8, OpenBSD 3.2, NetBSD 1.6 - give EPERM |
258 | .\" SunOS 5.8 - gives EBADF | |
259 | .\" Tru64 5.1b, HP-UX-11i, SunOS 5.7 - give 0 | |
847e0d88 | 260 | .PP |
c13182ef MK |
261 | The |
262 | .I pw_dir | |
263 | field contains the name of the initial working directory of the user. | |
2f0af33b MK |
264 | Login programs use the value of this field to initialize the |
265 | .B HOME | |
266 | environment variable for the login shell. | |
6b2fc294 | 267 | An application that wants to determine its user's home directory |
2f0af33b MK |
268 | should inspect the value of |
269 | .B HOME | |
270 | (rather than the value | |
94e9d9fe | 271 | .IR getpwuid(getuid())\->pw_dir ) |
6b2fc294 MK |
272 | since this allows the user to modify their notion of |
273 | "the home directory" during a login session. | |
274 | To determine the (initial) home directory of another user, | |
c13182ef | 275 | it is necessary to use |
94e9d9fe | 276 | .I getpwnam("username")\->pw_dir |
6b2fc294 | 277 | or similar. |
c6ec3685 MK |
278 | .SH EXAMPLE |
279 | The program below demonstrates the use of | |
280 | .BR getpwnam_r () | |
281 | to find the full username and user ID for the username | |
282 | supplied as a command-line argument. | |
847e0d88 | 283 | .PP |
207050fa | 284 | .EX |
c6ec3685 MK |
285 | #include <pwd.h> |
286 | #include <stdio.h> | |
287 | #include <stdlib.h> | |
288 | #include <unistd.h> | |
289 | #include <errno.h> | |
290 | ||
291 | int | |
292 | main(int argc, char *argv[]) | |
293 | { | |
294 | struct passwd pwd; | |
295 | struct passwd *result; | |
296 | char *buf; | |
297 | size_t bufsize; | |
298 | int s; | |
299 | ||
300 | if (argc != 2) { | |
301 | fprintf(stderr, "Usage: %s username\\n", argv[0]); | |
302 | exit(EXIT_FAILURE); | |
303 | } | |
304 | ||
305 | bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); | |
306 | if (bufsize == \-1) /* Value was indeterminate */ | |
307 | bufsize = 16384; /* Should be more than enough */ | |
308 | ||
309 | buf = malloc(bufsize); | |
310 | if (buf == NULL) { | |
311 | perror("malloc"); | |
312 | exit(EXIT_FAILURE); | |
313 | } | |
314 | ||
315 | s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result); | |
316 | if (result == NULL) { | |
317 | if (s == 0) | |
318 | printf("Not found\\n"); | |
319 | else { | |
320 | errno = s; | |
321 | perror("getpwnam_r"); | |
322 | } | |
323 | exit(EXIT_FAILURE); | |
324 | } | |
325 | ||
42afc407 | 326 | printf("Name: %s; UID: %ld\\n", pwd.pw_gecos, (long) pwd.pw_uid); |
c6ec3685 MK |
327 | exit(EXIT_SUCCESS); |
328 | } | |
207050fa | 329 | .EE |
47297adb | 330 | .SH SEE ALSO |
fea681da MK |
331 | .BR endpwent (3), |
332 | .BR fgetpwent (3), | |
333 | .BR getgrnam (3), | |
334 | .BR getpw (3), | |
335 | .BR getpwent (3), | |
1ed50462 | 336 | .BR getspnam (3), |
fea681da MK |
337 | .BR putpwent (3), |
338 | .BR setpwent (3), | |
339 | .BR passwd (5) |