Section: Linux Programmer's Manual (3)
mktemp - make a unique temporary filename
char *mktemp(char *template);
Feature Test Macro Requirements for glibc (see
- 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
function generates a unique temporary filename
The last six characters of template must
be XXXXXX and these are replaced with a string that makes the
Since it will be modified,
must not be a string constant, but should be declared as a character array.
function always returns template
If a unique name was created, the last six bytes of template
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,
is made an empty string, and
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
POSIX.1-2008 removes the specification of
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
is a security risk.
The race is avoided by
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