1.\" Copyright (c) 1989, 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)mktemp.3 6.10 (Berkeley) 4/19/91 33.\" $Id: mktemp.3,v 1.3 1993/11/29 22:06:55 jtc Exp $ 34.\" 35.Dd April 19, 1991 36.Dt MKTEMP 3 37.Os 38.Sh NAME 39.Nm mktemp 40.Nd make temporary file name (unique) 41.Sh SYNOPSIS 42.Fd #include <unistd.h> 43.Ft char * 44.Fn mktemp "char *template" 45.Ft int 46.Fn mkstemp "char *template" 47.Sh DESCRIPTION 48The 49.Fn mktemp 50function 51takes the given file name template and overwrites a portion of it 52to create a file name. 53This file name is unique and suitable for use 54by the application. 55The template may be any file name with some number of 56.Ql X Ns s 57appended 58to it, for example 59.Pa /tmp/temp.XXXX . 60The trailing 61.Ql X Ns s 62are replaced with the current process number and/or a 63unique letter combination. 64The number of unique file names 65.Fn mktemp 66can return depends on the number of 67.Ql X Ns s 68provided; six 69.Ql X Ns s 70will 71result in 72.Fn mktemp 73testing roughly 26 ** 6 combinations. 74.Pp 75The 76.Fn mkstemp 77function 78makes the same replacement to the template and creates the template file, 79mode 0600, returning a file descriptor opened for reading and writing. 80This avoids the race between testing for a file's existence and opening it 81for use. 82.Sh RETURN VALUES 83The 84.Fn mktemp 85function 86returns a pointer to the template on success and 87.Dv NULL 88on failure. 89The 90.Fn mkstemp 91function 92returns \-1 if no suitable file could be created. 93If either call fails an error code is placed in the global variable 94.Va errno . 95.Sh ERRORS 96The 97.Fn mktemp 98and 99.Fn mkstemp 100functions 101may set 102.Va errno 103to one of the following values: 104.Bl -tag -width Er 105.It Bq Er ENOTDIR 106The pathname portion of the template is not an existing directory. 107.El 108.Pp 109The 110.Fn mktemp 111and 112.Fn mkstemp 113functions 114may also set 115.Va errno 116to any value specified by the 117.Xr stat 2 118function. 119.Pp 120The 121.Fn mkstemp 122function 123may also set 124.Va errno 125to any value specified by the 126.Xr open 2 127function. 128.Sh SEE ALSO 129.Xr chmod 2 , 130.Xr getpid 2 , 131.Xr open 2 , 132.Xr stat 2 133.Sh HISTORY 134A 135.Nm mktemp 136function appeared in 137.At v7 . 138