mktemp — make a unique temporary filename
#include <stdlib.h>
char
*mktemp( |
char * | template) ; |
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
returns NULL on error (template
did not end in XXXXXX)
and template
otherwise. If the call was successful, the last six bytes of
template
will have
been modified in such a way that the resulting name is unique
(does not exist already). If the call was unsuccessful,
template
is made an
empty string.
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)
|