MKSTEMP(3C) Standard C Library Functions MKSTEMP(3C)


mkstemp, mkstemps, mkostemp, mkostemps, mkdtemp - make a unique file name
from a template and open the file


#include <stdlib.h>

int mkstemp(char *template);

int mkostemp(char *template, int flags);

int mkstemps(char *template, int slen);

int mkostemps(char *template, int slen, int flags);

char *mkdtemp(char *template);


The mkstemp() function replaces the contents of the string pointed to by
template by a unique file name, and returns a file descriptor for the
file open for reading and writing. The function thus prevents any
possible race condition between testing whether the file exists and
opening it for use. The string in template should look like a file name
with six trailing 'X's; mkstemp() replaces each 'X' with a character from
the portable file name character set. The characters are chosen such that
the resulting name does not duplicate the name of an existing file.

The mkstemps() function behaves the same as mkstemp(), except it permits
a suffix to exist in the template. The template should be of the form
/tmp/tmpXXXXXXsuffix. The slen parameter specifies the length of the
suffix string.

The mkostemp() and mkostemps are like their mkstemp() and mkstemps()
couterparts except that the flags argument is present and used to
supplement (as a bitwise inclusive-OR) flags to internal open() calls.

The mkdtemp() function makes the same replacement to the template as in
mktemp(3C) and creates the template directory using mkdir(2), passing a
mode argument of 0700.


Upon successful completion, mkstemp() returns an open file descriptor.
Otherwise -1 is returned if no suitable file could be created.


The mkstemp(), mkstemps(), and mkdtemp() functions can set errno to the
same values as lstat(2).

The mkstemp() and mkstemps() functions can set errno to the same values
as open(2).

The mkdtemp() function can set errno to the same values as mkdir(2).


It is possible to run out of letters.

The mkstemp() function does not check to determine whether the file name
part of template exceeds the maximum allowable file name length.

The tmpfile(3C) function is preferred over this function.

The mkstemp() function is frequently used to create a temporary file that
will be removed by the application before the application terminates.

The mkstemp() function has a transitional interface for 64-bit file
offsets. See lf64(5).


See attributes(5) for descriptions of the following attributes:

|Interface Stability | See below. |

The mkstemp() function is Standard. The mkstemps() and mkdtemp()
functions are Stable.


getpid(2), lstat(2), mkdir(2), open(2), tmpfile(3C), mktemp(3C),
attributes(5), lf64(5), standards(5)

April 19, 2013 MKSTEMP(3C)