mktemp(3)

1MKTEMP(3)                  Linux Programmer's Manual                 MKTEMP(3)
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NAME

6       mktemp - make a unique temporary filename
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SYNOPSIS

9       #include <stdlib.h>
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11       char *mktemp(char *template);
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13   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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15       mktemp(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
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DESCRIPTION

18       The  mktemp()  function generates a unique temporary filename from tem‐
19       plate.  The last six characters of template must be  XXXXXX  and  these
20       are  replaced  with  a string that makes the filename unique.  Since it
21       will be modified, template must not be a string constant, but should be
22       declared as a character array.
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RETURN VALUE

25       The  mktemp()  function  always returns template.  If a unique name was
26       created, the last six bytes of template will have been modified in such
27       a  way that the resulting name is unique (i.e., does not exist already)
28       If a unique name could not  be  created,  template  is  made  an  empty
29       string.
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ERRORS

32       EINVAL The last six characters of template were not XXXXXX.
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CONFORMING TO

35       4.3BSD,   POSIX.1-2001.   POSIX.1-2008  removes  the  specification  of
36       mktemp().
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NOTES

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

43       Never  use  mktemp().   Some  implementations follow 4.3BSD and replace
44       XXXXXX by the current process ID and a single letter, so that  at  most
45       26  different  names  can be returned.  Since on the one hand the names
46       are easy to guess, and on the other hand there is a race between  test‐
47       ing whether the name exists and opening the file, every use of mktemp()
48       is a security risk.  The race is avoided by mkstemp(3).
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COLOPHON

54       This page is part of release 3.22 of the Linux  man-pages  project.   A
55       description  of  the project, and information about reporting bugs, can
56       be found at http://www.kernel.org/doc/man-pages/.
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60GNU                               2008-08-06                         MKTEMP(3)