1 .\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl)
3 .\" %%%LICENSE_START(VERBATIM)
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9 .\" manual under the conditions for verbatim copying, provided that the
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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14 .\" manual page may be incorrect or out-of-date.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
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18 .\" which is licensed free of charge, as they might when working
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25 .\" 2003-11-15, aeb, added tmpnam_r
27 .TH TMPNAM 3 2021-03-22 "" "Linux Programmer's Manual"
29 tmpnam, tmpnam_r \- create a name for a temporary file
34 .BI "char *tmpnam(char *" s );
35 .BI "char *tmpnam_r(char *" s );
39 Feature Test Macro Requirements for glibc (see
40 .BR feature_test_macros (7)):
47 Up to and including glibc 2.19:
48 _BSD_SOURCE || _SVID_SOURCE
52 avoid using these functions; use
60 function returns a pointer to a string that is a valid filename,
61 and such that a file with this name did not exist at some point
62 in time, so that naive programmers may think it
63 a suitable name for a temporary file.
66 is NULL, this name is generated in an internal static buffer
67 and may be overwritten by the next call to
71 is not NULL, the name is copied to the character array (of length
78 is returned in case of success.
80 The created pathname has a directory prefix
94 function performs the same task as
96 but returns NULL (to indicate an error) if
100 These functions return a pointer to a unique temporary
101 filename, or NULL if a unique name cannot be generated.
103 No errors are defined.
105 For an explanation of the terms used in this section, see
113 Interface Attribute Value
116 T} Thread safety MT-Unsafe race:tmpnam/!s
119 T} Thread safety MT-Safe
126 SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
132 is a nonstandard extension that is also available
133 .\" Appears to be on Solaris
134 on a few other systems.
138 function generates a different string each time it is called,
142 If it is called more than
145 the behavior is implementation defined.
147 Although these functions generate names that are difficult to guess,
148 it is nevertheless possible that between the time that
149 the pathname is returned and the time that the program opens it,
150 another program might create that pathname using
152 or create it as a symbolic link.
153 This can lead to security holes.
154 To avoid such possibilities, use the
157 flag to open the pathname.
163 Portable applications that use threads cannot call
165 with a NULL argument if either
168 .B _POSIX_THREAD_SAFE_FUNCTIONS
171 Never use these functions.