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@(#)mktemp.3 8.1 (Berkeley) 6/4/93
.Dd June 4, 1993 .Dt MKTEMP 3 .Os .Sh NAME .Nm mktemp .Nd make temporary file name (unique) .Sh SYNOPSIS .Fd #include <unistd.h> .Ft char * .Fn mktemp "char *template" .Ft int .Fn mkstemp "char *template" .Sh DESCRIPTION The .Fn mktemp function takes the given file name template and overwrites a portion of it to create a file name. This file name is unique and suitable for use by the application. The template may be any file name with some number of .Ql X Ns s appended to it, for example
a /tmp/temp.XXXX . The trailing .Ql X Ns s are replaced with the current process number and/or a unique letter combination. The number of unique file names .Fn mktemp can return depends on the number of .Ql X Ns s provided; six .Ql X Ns s will result in .Fn mktemp testing roughly 26 ** 6 combinations.
p The .Fn mkstemp function makes the same replacement to the template and creates the template file, mode 0600, returning a file descriptor opened for reading and writing. This avoids the race between testing for a file's existence and opening it for use. .Sh RETURN VALUES The .Fn mktemp function returns a pointer to the template on success and .Dv NULL on failure. The .Fn mkstemp function returns -1 if no suitable file could be created. If either call fails an error code is placed in the global variable .Va errno . .Sh ERRORS The .Fn mktemp and .Fn mkstemp functions may set .Va errno to one of the following values: l -tag -width Er t Bq Er ENOTDIR The pathname portion of the template is not an existing directory. .El
p The .Fn mktemp and .Fn mkstemp functions may also set .Va errno to any value specified by the .Xr stat 2 function.
p The .Fn mkstemp function may also set .Va errno to any value specified by the .Xr open 2 function. .Sh SEE ALSO .Xr chmod 2 , .Xr getpid 2 , .Xr open 2 , .Xr stat 2 .Sh HISTORY A .Fn mktemp function appeared in .At v7 .