MKTEMP

NAME

mktemp - make a unique temporary file name

SYNOPSIS

#include <stdlib.h>

char *mktemp(char *template);

DESCRIPTION

The mktemp() function generates a unique temporary file name 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.

RETURN VALUE

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.

ERRORS

EINVAL: The last six characters of template were not XXXXXX.

CONFORMING TO

BSD 4.3. POSIX dictates tmpnam(3).

NOTE

The prototype is in <unistd.h> for libc4, libc5, glibc1; glibc2 follows the Single Unix Specification and has the prototype in <stdlib.h>.

BUGS

Never use mktemp(). Some implementations follow BSD 4.3 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).