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1 | .\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl) |
2 | .\" | |
93015253 | 3 | .\" %%%LICENSE_START(VERBATIM) |
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4 | .\" Permission is granted to make and distribute verbatim copies of this |
5 | .\" manual provided the copyright notice and this permission notice are | |
6 | .\" preserved on all copies. | |
7 | .\" | |
8 | .\" Permission is granted to copy and distribute modified versions of this | |
9 | .\" manual under the conditions for verbatim copying, provided that the | |
10 | .\" entire resulting derived work is distributed under the terms of a | |
11 | .\" permission notice identical to this one. | |
c13182ef | 12 | .\" |
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13 | .\" Since the Linux kernel and libraries are constantly changing, this |
14 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
15 | .\" responsibility for errors or omissions, or for damages resulting from | |
16 | .\" the use of the information contained herein. The author(s) may not | |
17 | .\" have taken the same level of care in the production of this manual, | |
18 | .\" which is licensed free of charge, as they might when working | |
19 | .\" professionally. | |
c13182ef | 20 | .\" |
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21 | .\" Formatted or processed versions of this manual, if unaccompanied by |
22 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 23 | .\" %%%LICENSE_END |
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24 | .\" |
25 | .\" 2003-11-15, aeb, added tmpnam_r | |
26 | .\" | |
4b8c67d9 | 27 | .TH TMPNAM 3 2017-09-15 "" "Linux Programmer's Manual" |
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28 | .SH NAME |
29 | tmpnam, tmpnam_r \- create a name for a temporary file | |
30 | .SH SYNOPSIS | |
31 | .nf | |
32 | .B #include <stdio.h> | |
dbfe9c70 | 33 | .PP |
fea681da | 34 | .BI "char *tmpnam(char *" s ); |
02301948 | 35 | .BI "char *tmpnam_r(char *" s ); |
fea681da | 36 | .fi |
68e4db0a | 37 | .PP |
02301948 MK |
38 | .in -4n |
39 | Feature Test Macro Requirements for glibc (see | |
40 | .BR feature_test_macros (7)): | |
41 | .in | |
68e4db0a | 42 | .PP |
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43 | .BR tmpnam_r () |
44 | .PD 0 | |
45 | .ad l | |
46 | .RS 4 | |
47 | .TP 4 | |
48 | Since glibc 2.19: | |
49 | _DEFAULT_SOURCE | |
50 | .TP | |
51 | Up to and including glibc 2.19: | |
52 | _BSD_SOURCE || _SVID_SOURCE | |
53 | .RE | |
54 | .ad | |
55 | .PD | |
fea681da | 56 | .SH DESCRIPTION |
fa90334d | 57 | .B Note: |
02301948 | 58 | avoid using these functions; use |
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59 | .BR mkstemp (3) |
60 | or | |
61 | .BR tmpfile (3) | |
62 | instead. | |
847e0d88 | 63 | .PP |
fea681da | 64 | The |
63aa9df0 | 65 | .BR tmpnam () |
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66 | function returns a pointer to a string that is a valid filename, |
67 | and such that a file with this name did not exist at some point | |
68 | in time, so that naive programmers may think it | |
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69 | a suitable name for a temporary file. |
70 | If the argument | |
fea681da | 71 | .I s |
e0268ba0 | 72 | is NULL, this name is generated in an internal static buffer |
fea681da | 73 | and may be overwritten by the next call to |
63aa9df0 | 74 | .BR tmpnam (). |
fea681da MK |
75 | If |
76 | .I s | |
77 | is not NULL, the name is copied to the character array (of length | |
78 | at least | |
79 | .IR L_tmpnam ) | |
80 | pointed to by | |
81 | .I s | |
82 | and the value | |
83 | .I s | |
84 | is returned in case of success. | |
dd3568a1 | 85 | .PP |
91d5e32f | 86 | The created pathname has a directory prefix |
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87 | .IR P_tmpdir . |
88 | (Both | |
89 | .I L_tmpnam | |
90 | and | |
91 | .I P_tmpdir | |
92 | are defined in | |
93 | .IR <stdio.h> , | |
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94 | just like the |
95 | .B TMP_MAX | |
96 | mentioned below.) | |
847e0d88 | 97 | .PP |
fea681da | 98 | The |
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99 | .BR tmpnam_r () |
100 | function performs the same task as | |
101 | .BR tmpnam (), | |
102 | but returns NULL (to indicate an error) if | |
103 | .I s | |
104 | is NULL. | |
105 | .SH RETURN VALUE | |
106 | These functions return a pointer to a unique temporary | |
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107 | filename, or NULL if a unique name cannot be generated. |
108 | .SH ERRORS | |
109 | No errors are defined. | |
70f5f10e | 110 | .SH ATTRIBUTES |
117ae581 PH |
111 | For an explanation of the terms used in this section, see |
112 | .BR attributes (7). | |
113 | .TS | |
114 | allbox; | |
115 | lb lb lb | |
116 | l l l. | |
117 | Interface Attribute Value | |
118 | T{ | |
70f5f10e | 119 | .BR tmpnam () |
9718ae80 | 120 | T} Thread safety MT-Unsafe race:tmpnam/!s |
117ae581 | 121 | T{ |
70f5f10e | 122 | .BR tmpnam_r () |
117ae581 PH |
123 | T} Thread safety MT-Safe |
124 | .TE | |
47297adb | 125 | .SH CONFORMING TO |
02301948 | 126 | .BR tmpnam (): |
2b2581ee | 127 | SVr4, 4.3BSD, C89, C99, POSIX.1-2001. |
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128 | POSIX.1-2008 marks |
129 | .BR tmpnam () | |
130 | as obsolete. | |
847e0d88 | 131 | .PP |
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132 | .BR tmpnam_r () |
133 | is a nonstandard extension that is also available | |
134 | .\" Appears to be on Solaris | |
135 | on a few other systems. | |
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136 | .SH NOTES |
137 | The | |
63aa9df0 | 138 | .BR tmpnam () |
fea681da | 139 | function generates a different string each time it is called, |
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140 | up to |
141 | .B TMP_MAX | |
142 | times. | |
143 | If it is called more than | |
144 | .B TMP_MAX | |
145 | times, | |
d9bfdb9c | 146 | the behavior is implementation defined. |
dd3568a1 | 147 | .PP |
02301948 | 148 | Although these functions generate names that are difficult to guess, |
3b6b5e8b | 149 | it is nevertheless possible that between the time that |
02301948 | 150 | the pathname is returned and the time that the program opens it, |
3b6b5e8b | 151 | another program might create that pathname using |
c13182ef | 152 | .BR open (2), |
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153 | or create it as a symbolic link. |
154 | This can lead to security holes. | |
c13182ef | 155 | To avoid such possibilities, use the |
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156 | .BR open (2) |
157 | .B O_EXCL | |
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158 | flag to open the pathname. |
159 | Or better yet, use | |
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160 | .BR mkstemp (3) |
161 | or | |
162 | .BR tmpfile (3). | |
dd3568a1 | 163 | .PP |
fea681da | 164 | Portable applications that use threads cannot call |
63aa9df0 | 165 | .BR tmpnam () |
c4bb193f | 166 | with a NULL argument if either |
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167 | .B _POSIX_THREADS |
168 | or | |
169 | .B _POSIX_THREAD_SAFE_FUNCTIONS | |
170 | is defined. | |
fea681da | 171 | .SH BUGS |
02301948 | 172 | Never use these functions. |
c13182ef | 173 | Use |
fea681da | 174 | .BR mkstemp (3) |
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175 | or |
176 | .BR tmpfile (3) | |
fea681da | 177 | instead. |
47297adb | 178 | .SH SEE ALSO |
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179 | .BR mkstemp (3), |
180 | .BR mktemp (3), | |
181 | .BR tempnam (3), | |
182 | .BR tmpfile (3) |