mktemp - make a unique temporary file name char *mktemp(char
*template); The mktemp() function generates a unique temporary
file name from tem- plate. 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. EINVAL The last six characters of template
were not XXXXXX. BSD 4.3. POSIX dictates tmpnam(3). 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 BSD
4.3 and replace XXXXXX by the cur