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

6       mkstemp, mkostemp, mkstemps, mkostemps - create a unique temporary file
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SYNOPSIS

9       #include <stdlib.h>
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11       int mkstemp(char *template);
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13       int mkostemp(char *template, int flags);
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15       int mkstemps(char *template, int suffixlen);
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17       int mkostemps(char *template, int suffixlen, int flags);
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19   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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21       mkstemp():
22           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
23           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
24           || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200112L
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26       mkostemp(): _GNU_SOURCE
27       mkstemps(): _BSD_SOURCE || _SVID_SOURCE
28       mkostemps(): _GNU_SOURCE
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DESCRIPTION

31       The mkstemp() function generates a unique temporary filename from  tem‐
32       plate,  creates and opens the file, and returns an open file descriptor
33       for the file.
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35       The last six characters of template must  be  "XXXXXX"  and  these  are
36       replaced  with  a string that makes the filename unique.  Since it will
37       be modified, template must not be a  string  constant,  but  should  be
38       declared as a character array.
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40       The file is created with permissions 0600, that is, read plus write for
41       owner only.  The returned file descriptor provides both read and  write
42       access  to  the file.  The file is opened with the open(2) O_EXCL flag,
43       guaranteeing that the caller is the process that creates the file.
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45       The mkostemp() function is like mkstemp(),  with  the  difference  that
46       flags  as  for  open(2)  may  be  specified  in  flags (e.g., O_APPEND,
47       O_SYNC).
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49       The mkstemps() function is like mkstemp(), except that  the  string  in
50       template  contains a suffix of suffixlen characters.  Thus, template is
51       of the form prefixXXXXXXsuffix, and the string XXXXXX  is  modified  as
52       for mkstemp().
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54       The   mkostemps()  function  is  to  mkstemps()  as  mkostemp()  is  to
55       mkstemp().
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RETURN VALUE

58       On success, these functions return the file descriptor of the temporary
59       file.  On error, -1 is returned, and errno is set appropriately.
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ERRORS

62       EEXIST Could  not create a unique temporary filename.  Now the contents
63              of template are undefined.
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65       EINVAL For mkstemp() and mkostemp(): The last six  characters  of  tem‐
66              plate were not XXXXXX; now template is unchanged.
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68              For  mkstemps() and mkostemps(): template is less than (6 + suf‐
69              fixlen) characters long, or the last  6  characters  before  the
70              suffix in template were not XXXXXX.
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72       These  functions  may  also  fail  with any of the errors described for
73       open(2).
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VERSIONS

76       mkostemp() is available since glibc 2.7.   mkstemps()  and  mkostemps()
77       are available since glibc 2.11.
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CONFORMING TO

80       mkstemp(): 4.3BSD, POSIX.1-2001.
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82       mkstemps(): unstandardized, but appears on several other systems.
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84       mkostemp() and mkostemps(): are glibc extensions.
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NOTES

87       In  glibc  versions  2.06 and earlier, the file is created with permis‐
88       sions 0666, that is, read and write for all users.  This  old  behavior
89       may  be  a security risk, especially since other UNIX flavors use 0600,
90       and  somebody  might  overlook  this  detail  when  porting   programs.
91       POSIX.1-2008  adds  a  requirement  that  the file be created with mode
92       0600.
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94       More generally, the POSIX specification of mkstemp() does not say  any‐
95       thing  about  file  modes, so the application should make sure its file
96       mode creation mask (see umask(2)) is set appropriately  before  calling
97       mkstemp() (and mkostemp()).
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99       The  prototype  for mktemp() is in <unistd.h> for libc4, libc5, glibc1;
100       glibc2 follows POSIX.1 and has the prototype in <stdlib.h>.
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SEE ALSO

103       mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3)
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COLOPHON

106       This page is part of release 3.53 of the Linux  man-pages  project.   A
107       description  of  the project, and information about reporting bugs, can
108       be found at http://www.kernel.org/doc/man-pages/.
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112GNU                               2012-12-21                        MKSTEMP(3)
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