mktemp - make a unique temporary filename
#include <stdlib.h>
char *mktemp(char *template);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
mktemp():
- Since glibc 2.12:
- (_XOPEN_SOURCE >= 500) && !
(_POSIX_C_SOURCE >= 200112L)
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
- Before glibc 2.12:
- _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
Never use this function; see BUGS.
The
mktemp() function generates a unique temporary filename from
template. The last six characters of
template must be XXXXXX and
these are replaced with a string that makes the filename unique. Since it will
be modified,
template must not be a string constant, but should be
declared as a character array.
The
mktemp() function always returns
template. If a unique name
was created, the last six bytes of
template will have been modified in
such a way that the resulting name is unique (i.e., does not exist already) If
a unique name could not be created,
template is made an empty string,
and
errno is set to indicate the error.
- EINVAL
- The last six characters of template were not XXXXXX.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
mktemp () |
Thread safety |
MT-Safe |
4.3BSD, POSIX.1-2001. POSIX.1-2008 removes the specification of
mktemp().
Never use
mktemp(). Some implementations follow 4.3BSD and replace XXXXXX
by the current process ID and a single letter, so that at most 26 different
names can be returned. Since on the one hand the names are easy to guess, and
on the other hand there is a race between testing whether the name exists and
opening the file, every use of
mktemp() is a security risk. The race is
avoided by
mkstemp(3) and
mkdtemp(3).
mktemp(1),
mkdtemp(3),
mkstemp(3),
tempnam(3),
tmpfile(3),
tmpnam(3)