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MKSTEMP(3) Linux Programmer's Manual MKSTEMP(3) NAME mkstemp, mkostemp, mkstemps, mkostemps - create a unique temporary file SYNOPSIS #include <stdlib.h> int mkstemp(char *template); int mkostemp(char *template, int flags); int mkstemps(char *template, int suffixlen); int mkostemps(char *template, int suffixlen, int flags); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): mkstemp(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200112L mkostemp(): _GNU_SOURCE mkstemps(): _BSD_SOURCE || _SVID_SOURCE mkostemps(): _GNU_SOURCE DESCRIPTION The mkstemp() function generates a unique temporary filename from tem- plate, creates and opens the file, and returns an open file descriptor for the file. The last six characters of template must be "XXXXXX" and these are re- placed with a string that makes the filename unique. Since it will be modified, template must not be a string constant, but should be de- clared as a character array. The file is created with permissions 0600, that is, read plus write for owner only. The returned file descriptor provides both read and write access to the file. The file is opened with the open(2) O_EXCL flag, guaranteeing that the caller is the process that creates the file. The mkostemp() function is like mkstemp(), with the difference that the following bits--with the same meaning as for open(2)--may be specified in flags: O_APPEND, O_CLOEXEC, and O_SYNC. Note that when creating the file, mkostemp() includes the values O_RDWR, O_CREAT, and O_EXCL in the flags argument given to open(2); including these values in the flags argument given to mkostemp() is unnecessary, and produces errors on some systems. The mkstemps() function is like mkstemp(), except that the string in template contains a suffix of suffixlen characters. Thus, template is of the form prefixXXXXXXsuffix, and the string XXXXXX is modified as for mkstemp(). The mkostemps() function is to mkstemps() as mkostemp() is to mk- stemp(). RETURN VALUE On success, these functions return the file descriptor of the temporary file. On error, -1 is returned, and errno is set appropriately. ERRORS EEXIST Could not create a unique temporary filename. Now the contents of template are undefined. EINVAL For mkstemp() and mkostemp(): The last six characters of tem- plate were not XXXXXX; now template is unchanged. For mkstemps() and mkostemps(): template is less than (6 + suf- fixlen) characters long, or the last 6 characters before the suffix in template were not XXXXXX. These functions may also fail with any of the errors described for open(2). VERSIONS mkostemp() is available since glibc 2.7. mkstemps() and mkostemps() are available since glibc 2.11. ATTRIBUTES Multithreading (see pthreads(7)) The mkstemp(), mkostemp(), mkstemps(), and mkostemps() functions are thread-safe. CONFORMING TO mkstemp(): 4.3BSD, POSIX.1-2001. mkstemps(): unstandardized, but appears on several other systems. mkostemp() and mkostemps(): are glibc extensions. NOTES In glibc versions 2.06 and earlier, the file is created with permis- sions 0666, that is, read and write for all users. This old behavior may be a security risk, especially since other UNIX flavors use 0600, and somebody might overlook this detail when porting programs. POSIX.1-2008 adds a requirement that the file be created with mode 0600. More generally, the POSIX specification of mkstemp() does not say any- thing about file modes, so the application should make sure its file mode creation mask (see umask(2)) is set appropriately before calling mkstemp() (and mkostemp()). SEE ALSO mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3) COLOPHON This page is part of release 3.74 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/. GNU 2014-08-19 MKSTEMP(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON
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