MKTEMP Section: Linux Programmer's Manual (3) Updated: April 3, 2025 Index   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().   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   SEE ALSO   Index NAME SYNOPSIS DESCRIPTION RETURN VALUE ERRORS CONFORMING TO NOTE BUGS SEE ALSO This document was created by using the manual pages. Time: 11:58:05 GMT, March 24, 2025