1MKSTEMP(3P)                POSIX Programmer's Manual               MKSTEMP(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       mkstemp - make a unique filename
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SYNOPSIS

15       #include <stdlib.h>
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17       int mkstemp(char *template);
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DESCRIPTION

21       The mkstemp() function shall replace the contents of the string pointed
22       to  by  template by a unique filename, and return a file descriptor for
23       the file open for reading and writing.  The function thus prevents  any
24       possible  race  condition  between  testing whether the file exists and
25       opening it for use. The string in template should look like a  filename
26       with  six  trailing 'X' s; mkstemp() replaces each 'X' with a character
27       from the portable filename character set.  The  characters  are  chosen
28       such that the resulting name does not duplicate the name of an existing
29       file at the time of a call to mkstemp().
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RETURN VALUE

32       Upon  successful  completion,  mkstemp()  shall  return  an  open  file
33       descriptor.  Otherwise,  -1 shall be returned if no suitable file could
34       be created.
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ERRORS

37       No errors are defined.
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39       The following sections are informative.
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EXAMPLES

42   Generating a Filename
43       The following example creates a file with a 10-character name beginning
44       with  the characters "file" and opens the file for reading and writing.
45       The value returned as the value of fd is a file descriptor that identi‐
46       fies the file.
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49              #include <stdlib.h>
50              ...
51              char template[] = "/tmp/fileXXXXXX";
52              int fd;
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55              fd = mkstemp(template);
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APPLICATION USAGE

58       It is possible to run out of letters.
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60       The mkstemp() function need not check to determine whether the filename
61       part of template exceeds the maximum allowable filename length.
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RATIONALE

64       None.
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FUTURE DIRECTIONS

67       None.
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SEE ALSO

70       getpid(), open(), tmpfile(), tmpnam(), the Base Definitions  volume  of
71       IEEE Std 1003.1-2001, <stdlib.h>
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74       Portions  of  this text are reprinted and reproduced in electronic form
75       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
76       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
77       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
78       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
79       event of any discrepancy between this version and the original IEEE and
80       The  Open Group Standard, the original IEEE and The Open Group Standard
81       is the referee document. The original Standard can be  obtained  online
82       at http://www.opengroup.org/unix/online.html .
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86IEEE/The Open Group                  2003                          MKSTEMP(3P)
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