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umask(1)		    General Commands Manual		      umask(1)

NAME
       umask - set or display the file mode creation mask

SYNOPSIS
   Set Mask
   Display Mask
DESCRIPTION
       The  command  sets the value of the file	mode creation mask or displays
       the current one.	 The mask affects the initial value of the  file  mode
       (permission) bits for subsequently created files.

   Setting the File Mode Creation Mask
       The  command  sets  a new file mode creation mask for the current shell
       execution environment.  mask can	be a symbolic or numeric (obsolescent)
       value.

       A  symbolic  mask provides a flexible way of modifying the mask permis-
       sion bits individually or as a group.  A	numeric	mask specifies all the
       permission bits at one time.

       When  a	mask is	specified, no output is	written	to standard output.  A
       symbolic	mask replaces or modifies the current file mode	creation mask.
       It  is specified	as a comma-separated list of operations	in the follow-
       ing format.  Whitespace is not permitted.

	      [who][operator][permissions][, ...]

       The fields can have the following values:

	      who	     One or more of the	following letters:

				  Modify permissions for user (owner).
				  Modify permissions for group.
				  Modify permissions for others.

			     Or:

				  Modify permissions for all
					 =

	      operator	     One of the	following symbols:

				  Add	 permissions to	the existing mask  for
					 who.
				  Delete permissions  from  the	 existing mask
					 for who.
				  Replace the existing mask for
					 who with permissions.

	      permissions    One or more of the	following letters:

				  The read permission.

				  The write permission.

				  The execute/search permission.

       If one or two of	the fields are omitted,	the following table applies:
							       |
      Format Entered	    Effect			       | Input	 Equals
      ---------------------------------------------------------+----------------

      who		    Delete current permissions for who |
      operator		    No action			       |	 (none)
      permissions	    Equal to:			       |
			    Delete current permissions for who |
			    No action			       |	 (none)
			    No action			       |	 (none)
      whopermissions	    Equal to:			       |
      operatorpermissions   Equal to:			       |
       A numeric mask replaces the current file	mode  creation	mask.	It  is
       specified as an unsigned	octal integer, constructed from	the logical OR
       (sum) of	the following mode bits	(leading zeros can be omitted):

   Displaying the Current Mask Value
       To display the current file mode	creation mask value, use  one  of  the
       commands:

	      Print the	current	file mode creation mask	in a symbolic format:

			     The   characters	(read),	  (write),  and	 (exe-
			     cute/search) represent the	bits that are clear in
			     the  mask for (user/owner), (group), and (other).
			     All other bits are	set.

	      Print the	current	file mode creation mask	as an octal value.

			     The zero bits in the numeric value	correspond  to
			     the  displayed  and  permission characters	in the
			     symbolic value.  The  one	bits  in  the  numeric
			     value  correspond to the missing permission char-
			     acters in the symbolic value.

			     Depending on implementation, the display consists
			     of	 one  to four octal digits; the	first digit is
			     always zero (see  DEPENDENCIES).	The  rightmost
			     three  digits  (leading  zeros implied as needed)
			     represent the bits	that are set or	clear  in  the
			     mask.

       Both  forms produce output that can be used as the mask argument	to set
       the mask	in a subsequent	command.

   General Operation
       When a new file is created (see creat(2)), each bit that	is set in  the
       file  mode creation mask	causes the corresponding permission bit	in the
       the file	mode to	be cleared  (disabled).	  Conversely,  bits  that  are
       clear  in the mask allow	the corresponding file mode bits to be enabled
       in newly	created	files.

       For example, the	mask (octal disables group  and	 other	write  permis-
       sions.	As  a result, files normally created with a file mode shown by
       the command as (octal become mode (octal	while files created with  file
       mode (octal become mode (octal

       Note  that the file creation mode mask does not affect the set-user-id,
       set-group-id, or	"sticky" bits.

       The file	creation mode mask is also used	by the command (see chmod(1)).

       Since affects the current shell execution environment, it is  generally
       provided	as a shell regular built-in (see DEPENDENCIES).

       If  is  called in a subshell or separate	utility	execution environment,
       such as one of the following:

       it does not affect the file mode	creation mask of the calling  environ-
       ment.

       The default mask	is (octal

RETURN VALUE
       exits with one of the following values:

	      The file mode creation mask was successfully changed
		     or	no mask	operand	was supplied.
	      An error occurred.

EXAMPLES
       In these	examples, each line show an alternate way of accomplishing the
       same task.

       Set the value to	produce	read and  write	 permissions  for  the	file's
       owner  and  read	 permissions  for all others displays on newly created
       files):

       Set the value to	produce	read, and write	 permissions  for  the	file's
       owner,  read-only  for others users in the same group, and no access to
       others

       Set the value to	deny read, write, and execute permissions to everyone

       Add the write permission	to the current mask for	everyone (there	is  no
       equivalent numeric mode):

WARNINGS
       If  you	set  a	mask  that  prevents read or write access for the user
       (owner),	many programs, such as editors,	that  create  temporary	 files
       will fail because they cannot access the	file data.

DEPENDENCIES
       The  command  is	 implemented both as a separate	executable file	and as
       built-in	shell commands.

   POSIX Shell and Separate File
       All features are	supported (see sh-posix(1)).  The numeric mask display
       uses a minimum of two digits.

   Korn	Shell
       The  option  is	not  supported in the Korn shell built-in command (see
       ksh(1)).	 The numeric mask display uses a minimum of two	digits.

   C Shell
       The option and symbolic mask values are not supported in	 the  C	 shell
       built-in	command	(see csh(1)).  The numeric mask	display	uses a minimum
       of one digit.

SEE ALSO
       chmod(1),  csh(1),  ksh(1),  sh-posix(1),  sh(1),  chmod(2),  creat(2),
       umask(2).

STANDARDS CONFORMANCE
								      umask(1)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLES | WARNINGS | DEPENDENCIES | SEE ALSO | STANDARDS CONFORMANCE

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