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NAME

     umask - set file creation mode mask

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/stat.h>

     mode_t
     umask(mode_t numask);

DESCRIPTION

     The umask() routine sets the process’s file mode creation mask to numask
     and returns the previous value of the mask.  The 9 low-order access
     permission bits of numask are used by system calls, including open(2),
     mkdir(2), and mkfifo(2), to turn off corresponding bits requested in file
     mode.  (See chmod(2)).  This clearing allows each user to restrict the
     default access to his files.

     The default mask value is S_IWGRP|S_IWOTH (022, write access for the
     owner only).  Child processes inherit the mask of the calling process.

RETURN VALUES

     The previous value of the file mode mask is returned by the call.

ERRORS

     The umask() system call is always successful.

SEE ALSO

     chmod(2), mkfifo(2), mknod(2), open(2)

STANDARDS

     The umask() system call is expected to conform to ISO/IEC 9945-1:1990
     (“POSIX.1”).

HISTORY

     The umask() function appeared in Version 7 AT&T UNIX.