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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | BUGS | SEE ALSO | COLOPHON |
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TMPNAM(3) Linux Programmer's Manual TMPNAM(3)
tmpnam, tmpnam_r - create a name for a temporary file
#include <stdio.h>
char *tmpnam(char *s);
char *tmpnam_r(char *s);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
tmpnam_r()
Since glibc 2.19:
_DEFAULT_SOURCE
Up to and including glibc 2.19:
_BSD_SOURCE || _SVID_SOURCE
Note: avoid using these functions; use mkstemp(3) or tmpfile(3)
instead.
The tmpnam() function returns a pointer to a string that is a valid
filename, and such that a file with this name did not exist at some
point in time, so that naive programmers may think it a suitable name
for a temporary file. If the argument s is NULL, this name is
generated in an internal static buffer and may be overwritten by the
next call to tmpnam(). If s is not NULL, the name is copied to the
character array (of length at least L_tmpnam) pointed to by s and the
value s is returned in case of success.
The created pathname has a directory prefix P_tmpdir. (Both L_tmpnam
and P_tmpdir are defined in <stdio.h>, just like the TMP_MAX
mentioned below.)
The tmpnam_r() function performs the same task as tmpnam(), but
returns NULL (to indicate an error) if s is NULL.
These functions return a pointer to a unique temporary filename, or
NULL if a unique name cannot be generated.
No errors are defined.
For an explanation of the terms used in this section, see
attributes(7).
┌───────────┬───────────────┬──────────────────────────┐
│Interface │ Attribute │ Value │
├───────────┼───────────────┼──────────────────────────┤
│tmpnam() │ Thread safety │ MT-Unsafe race:tmpnam/!s │
├───────────┼───────────────┼──────────────────────────┤
│tmpnam_r() │ Thread safety │ MT-Safe │
└───────────┴───────────────┴──────────────────────────┘
tmpnam(): SVr4, 4.3BSD, C89, C99, POSIX.1-2001. POSIX.1-2008 marks
tmpnam() as obsolete.
tmpnam_r() is a nonstandard extension that is also available on a few
other systems.
The tmpnam() function generates a different string each time it is
called, up to TMP_MAX times. If it is called more than TMP_MAX
times, the behavior is implementation defined.
Although these functions generate names that are difficult to guess,
it is nevertheless possible that between the time that the pathname
is returned and the time that the program opens it, another program
might create that pathname using open(2), or create it as a symbolic
link. This can lead to security holes. To avoid such possibilities,
use the open(2) O_EXCL flag to open the pathname. Or better yet, use
mkstemp(3) or tmpfile(3).
Portable applications that use threads cannot call tmpnam() with a
NULL argument if either _POSIX_THREADS or
_POSIX_THREAD_SAFE_FUNCTIONS is defined.
Never use these functions. Use mkstemp(3) or tmpfile(3) instead.
mkstemp(3), mktemp(3), tempnam(3), tmpfile(3)
This page is part of release 4.15 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2017-09-15 TMPNAM(3)
Pages that refer to this page: getpid(2), mkdtemp(3), mkstemp(3), mktemp(3), stdio(3), tempnam(3), tmpfile(3)
Copyright and license for this manual page
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