mktemp - make a unique temporary file name
char *mktemp(char *template);
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,
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 last six characters of template were not XXXXXX.
BSD 4.3. POSIX dictates
The prototype is in
for libc4, libc5, glibc1; glibc2 follows the Single Unix Specification
and has the prototype in
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