mkstemp — create a unique temporary file
#include <stdlib.h>
int
mkstemp( |
char * | template) ; |
The mkstemp
() 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. The file is then created with mode read/write 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
constant, but should be declared as a character array. The
file is opened with the open(2) O_EXCL
flag, guaranteeing that when
mkstemp
() returns successfully
we are the only user.
On success, the mkstemp
()
function returns the file descriptor of the temporary file.
On error, −1 is returned, and errno
is set appropriately.
Could not create a unique temporary filename. Now
the contents of template
are
undefined.
The last six characters of template
were not XXXXXX.
Now template
is
unchanged.
The old behaviour (creating a file 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 modes, so the application should make
sure its umask is set appropriately before calling
mkstemp
().
The prototype is in <unistd.h>
for libc4,
libc5, glibc1; glibc2 follows the Single Unix Specification
and has the prototype in <stdlib.h>
.
mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3)
|