mktemp - make a unique temporary filename
Standard C library (libc, -lc)
#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 >= 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
Before glibc 2.12:
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500Never 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.
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 |
None.
4.3BSD, POSIX.1-2001. Removed in POSIX.1-2008.
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).