1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
2 .\" and Copyright (C) 2008, Michael Kerrisk <mtk.manpages@gmail.com>
4 .\" %%%LICENSE_START(VERBATIM)
5 .\" Permission is granted to make and distribute verbatim copies of this
6 .\" manual provided the copyright notice and this permission notice are
7 .\" preserved on all copies.
9 .\" Permission is granted to copy and distribute modified versions of this
10 .\" manual under the conditions for verbatim copying, provided that the
11 .\" entire resulting derived work is distributed under the terms of a
12 .\" permission notice identical to this one.
14 .\" Since the Linux kernel and libraries are constantly changing, this
15 .\" manual page may be incorrect or out-of-date. The author(s) assume no
16 .\" responsibility for errors or omissions, or for damages resulting from
17 .\" the use of the information contained herein. The author(s) may not
18 .\" have taken the same level of care in the production of this manual,
19 .\" which is licensed free of charge, as they might when working
22 .\" Formatted or processed versions of this manual, if unaccompanied by
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26 .\" References consulted:
27 .\" Linux libc source code
28 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
30 .\" Modified Sat Jul 24 18:48:48 1993 by Rik Faith (faith@cs.unc.edu)
31 .\" Modified 980310, aeb
32 .\" Modified 990328, aeb
33 .\" 2008-06-19, mtk, Added mkostemp(); various other changes
35 .TH MKSTEMP 3 2012-12-21 "GNU" "Linux Programmer's Manual"
37 mkstemp, mkostemp, mkstemps, mkostemps \- create a unique temporary file
40 .B #include <stdlib.h>
42 .BI "int mkstemp(char *" template );
44 .BI "int mkostemp(char *" template ", int " flags );
46 .BI "int mkstemps(char *" template ", int " suffixlen );
48 .BI "int mkostemps(char *" template ", int " suffixlen ", int " flags );
52 Feature Test Macro Requirements for glibc (see
53 .BR feature_test_macros (7)):
60 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
61 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
63 || /* Since glibc 2.12: */ _POSIX_C_SOURCE\ >=\ 200112L
72 _BSD_SOURCE || _SVID_SOURCE
79 function generates a unique temporary filename from
81 creates and opens the file,
82 and returns an open file descriptor for the file.
84 The last six characters of
86 must be "XXXXXX" and these are replaced with a string that makes the
88 Since it will be modified,
90 must not be a string constant, but should be declared as a character array.
92 The file is created with
93 permissions 0600, that is, read plus write for owner only.
94 The returned file descriptor provides both read and write access to the file.
95 The file is opened with the
98 flag, guaranteeing that the caller is the process that creates the file.
104 with the difference that flags as for
116 except that the string in
124 .IR "prefixXXXXXXsuffix" ,
125 and the string XXXXXX is modified as for
137 On success, these functions return the file descriptor
138 of the temporary file.
139 On error, \-1 is returned, and
141 is set appropriately.
145 Could not create a unique temporary filename.
146 Now the contents of \fItemplate\fP are undefined.
153 The last six characters of \fItemplate\fP were not XXXXXX;
154 now \fItemplate\fP is unchanged.
163 characters long, or the last 6 characters before the suffix in
167 These functions may also fail with any of the errors described for
171 is available since glibc 2.7.
175 are available since glibc 2.11.
178 4.3BSD, POSIX.1-2001.
181 unstandardized, but appears on several other systems.
182 .\" mkstemps() appears to be at least on the BSDs, Mac OS X, Solaris,
188 are glibc extensions.
190 In glibc versions 2.06 and earlier, the file is created with permissions 0666,
191 that is, read and write for all users.
192 This old behavior may be
193 a security risk, especially since other UNIX flavors use 0600,
194 and somebody might overlook this detail when porting programs.
195 POSIX.1-2008 adds a requirement that the file be created with mode 0600.
197 More generally, the POSIX specification of
199 does not say anything
200 about file modes, so the application should make sure its
201 file mode creation mask (see
203 is set appropriately before calling
212 for libc4, libc5, glibc1; glibc2 follows POSIX.1 and has the prototype in