MKTEMP(3) Linux Programmer's Manual MKTEMP(3)
mktemp - make a unique temporary filename
char *mktemp(char *template);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
Since glibc 2.12:
_BSD_SOURCE || _SVID_SOURCE ||
(_XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
!(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
Before glibc 2.12:
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
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.
4.3BSD, POSIX.1-2001. POSIX.1-2008 removes the specification of mktemp().
The prototype is in <unistd.h> for libc4, libc5, glibc1; glibc2 follows the Single UNIX
Specification and has the prototype in <stdlib.h>.
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).
mkstemp(3), tempnam(3), tmpfile(3), tmpnam(3)
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GNU 2013-04-19 MKTEMP(3)