The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group


umask - set and get file mode creation mask


#include <sys/types.h>
#include <sys/stat.h>

mode_t umask(mode_t cmask);


The umask() function sets the process' file mode creation mask to cmask and returns the previous value of the mask. Only the file permission bits of cmask (see <sys/stat.h>) are used; the meaning of the other bits is implementation-dependent.

The process' file mode creation mask is used during open(), creat(), mkdir() and mkfifo() to turn off permission bits in the mode argument supplied. Bit positions that are set in cmask are cleared in the mode of the created file.


The file permission bits in the value returned by umask() will be the previous value of the file mode creation mask. The state of any other bits in that value is unspecified, except that a subsequent call to umask() with the returned value as cmask will leave the state of the mask the same as its state before the first call, including any unspecified use of those bits.


No errors are defined.








creat(), mkdir(), mkfifo(), open(), <sys/stat.h>, <sys/types.h>.


Derived from Issue 1 of the SVID.

UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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