MKSTEMP(3) Linux Programmer's Manual MKSTEMP(3)
NAME
mkstemp - create a unique temporary file(1,n)
SYNOPSIS
#include <stdlib.h>
int mkstemp(char *template);
DESCRIPTION
The mkstemp() function generates a unique temporary file(1,n) name from tem-
plate. The last six characters of template must be XXXXXX and these
are replaced with a string(3,n) that makes the filename unique. The file(1,n) is
then created with mode read(2,n,1 builtins)/write(1,2) and permissions 0666 (glibc 2.0.6 and
earlier), 0600 (glibc 2.0.7 and later). Since it will be modified,
template must not be a string(3,n) constant, but should be declared as a
character array. The file(1,n) is opened with the O_EXCL flag, guaranteeing
that when mkstemp returns successfully we are the only user.
RETURN VALUE
The mkstemp() function returns the file(1,n) descriptor fd of the temporary
file(1,n) or -1 on error.
ERRORS
EEXIST Could not create a unique temporary filename. Now the contents
of template are undefined.
EINVAL The last six characters of template were not XXXXXX. Now tem-
plate is unchanged.
NOTES
The old behaviour (creating a file(1,n) with mode 0666) may be a security
risk, especially since other Unix flavours use 0600, and somebody might
overlook this detail when porting programs.
More generally, the POSIX specification does not say anything about
file(1,n) modes, so the application should make sure its umask is set(7,n,1 builtins) appro-
priately before calling mkstemp.
CONFORMING TO
BSD 4.3, POSIX 1003.1-2001
NOTE
The prototype is in(1,8) <unistd.h> for libc4, libc5, glibc1; glibc2 follows
the Single Unix Specification and has the prototype in(1,8) <stdlib.h>.
SEE ALSO
mkdtemp(3), mktemp(1,3)(3), tempnam(3), tmpfile(3), tmpnam(3)
GNU 2001-12-23 MKSTEMP(3)