umask



UMASK(2)                      System Calls Manual                     UMASK(2)


NAME

     umask - set file creation mode mask


SYNOPSIS

     #include <sys/types.h>
     #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.  Only the read, write, and
     execute file permission bits of numask are honored, all others are
     ignored.

     The file mode creation mask is used by the bind(2), mkdir(2), mkdirat(2),
     mkfifo(2), mkfifoat(2), mknod(2), mknodat(2), open(2) and openat(2)
     system calls to turn off corresponding bits requested in the 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() function is always successful.


SEE ALSO

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


STANDARDS

     The umask() function conforms to IEEE Std 1003.1-2008 (``POSIX.1'').


HISTORY

     The umask() system call first appeared in Version 7 AT&T UNIX.

OpenBSD 5.9                    October 12, 2015                    OpenBSD 5.9

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