User Commands                                            umask(1)


NAME

     umask - get or set the file mode creation mask


SYNOPSIS

     /usr/bin/umask [-S] [mask]

  sh
     umask [ooo]

  csh
     umask [ooo]

  ksh
     umask [-S] [mask]

  ksh93
     umask [-S] [mask]


DESCRIPTION

     The umask utility sets the file mode creation  mask  of  the
     current  shell  execution environment to the value specified
     by the mask operand. This mask affects the initial value  of
     the  file  permission bits of subsequently created files. If
     umask is called in a subshell or separate utility  execution
     environment, such as one of the following:

       (umask 002)
       nohup umask ...
       find . -exec umask ...

     it does not affect  the  file  mode  creation  mask  of  the
     caller's  environment.   For this reason, the /usr/bin/umask
     utility cannot be used to change the  umask  in  an  ongoing
     session.  Its usefulness is limited to checking the caller's
     umask. To change the umask of an ongoing  session  you  must
     use one of the shell builtins.

     If the mask operand is  not  specified,  the  umask  utility
     writes  the  value of the invoking process's file mode crea-
     tion mask to standard output.

  sh

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User Commands                                            umask(1)

     The user file-creation mode mask is set to ooo.   The  three
     octal  digits  refer  to  read/write/execute permissions for
     owner,  group,  and  other,  respectively   (see   chmod(1),
     chmod(2),  and umask(2)).  The value of each specified digit
     is subtracted from the corresponding ``digit'' specified  by
     the  system  for the creation of a file (see creat(2)).  For
     example, umask 022 removes write permission  for  group  and
     other.   Files  (and directories) normally created with mode
     777 become mode 755.  Files (and directories)  created  with
     mode 666 become mode 644).

         o    If ooo is omitted, the current value of the mask is
              printed.

         o    umask is recognized and executed by the shell.

         o    umask can be included in the user's  .profile  (see
              profile(4))  and  invoked at login to automatically
              set the user's permissions on files or  directories
              created.

  csh
     See the description above for  the  Bourne  shell  (sh)umask
     built-in.

  ksh
     The user file-creation mask is set to mask.  mask can either
     be  an  octal  number  or  a  symbolic value as described in
     chmod(1).  If a symbolic value is given, the new umask value
     is the complement of the result of applying mask to the com-
     plement of the previous umask value. If mask is omitted, the
     current value of the mask is printed.

  ksh93
     umask sets the file creation mask of the current shell  exe-
     cution  environment  to  the  value  specified  by  the mask
     operand. This mask affects the file permission bits of  sub-
     sequently created files.  mask can either be an octal number
     or a symbolic value as described in chmod(1). If a  symbolic
     value  is  specified, the new file creation mask is the com-
     plement of the result of applying mask to the complement  of
     the  current  file  creation mask. If mask is not specified,
     umask writes the value of the file  creation  mask  for  the
     current process to standard output.


OPTIONS

  ksh
     The following option is  supported  for  /usr/bin/umask  and
     umask in ksh:

     -S    Produces symbolic output.

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User Commands                                            umask(1)

     The default output style is unspecified, but will be  recog-
     nized on a subsequent invocation of umask on the same system
     as a mask operand to restore the previous file mode creation
     mask.

  ksh93
     The following option is supported in ksh93:

     -S    Causes the file creation mask to be written or treated
           as a symbolic value rather than an octal number.


OPERANDS

     The following operand is supported:

     mask    A string specifying the new file mode creation mask.
             The  string  is  treated in the same way as the mode
             operand described in the chmod(1) manual page.

             For a symbolic_mode value, the new value of the file
             mode  creation mask is the logical complement of the
             file permission bits portion of the file mode speci-
             fied by the symbolic_mode string.

             In a symbolic_mode value, the permissions op charac-
             ters + and - are interpreted relative to the current
             file mode creation mask.  + causes the bits for  the
             indicated  permissions to be cleared in the mask.  -
             causes the bits of the indicated permissions  to  be
             set in the mask.

             The interpretation of mode values that specify  file
             mode  bits  other  than  the file permission bits is
             unspecified.

             The file mode creation mask is set to the  resulting
             numeric value.

             The default output of a prior invocation of umask on
             the  same system with no operand will also be recog-
             nized as a mask  operand.  The  use  of  an  operand
             obtained  in this way is not obsolescent, even if it
             is an octal number.


OUTPUT

     When the mask operand is not specified,  the  umask  utility
     will  write  a  message to standard output that can later be
     used as a umask mask operand.

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User Commands                                            umask(1)

     If -S is specified, the message will  be  in  the  following
     format:

       "u=%s,g=%s,o=%s\n", owner permissions, group permissions, \
                               other permissions

     where the three values will be combinations of letters  from
     the  set  {r,  w, x}. The presence of a letter will indicate
     that the corresponding bit is clear in the file  mode  crea-
     tion mask.

     If a mask operand is specified,  there  will  be  no  output
     written to standard output.


EXAMPLES

     Example 1 Using the umask Command

     The examples in this section  refer  to  the  /usr/bin/umask
     utility and the ksh umask builtin.

     Either of the commands:

       umask a=rx,ug+w
       umask 002

     sets the mode mask so that subsequently created  files  have
     their S_IWOTH bit cleared.

     After setting the mode mask with either of  the  above  com-
     mands,  the  umask  command can be used to write the current
     value of the mode mask:

       example$ umask
       0002

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User Commands                                            umask(1)

     The output format is unspecified, but historical implementa-
     tions use the obsolescent octal integer mode format.

       example$ umask -S
       u=rwx,g=rwx,o=rx

     Either of these outputs can be used as the mask operand to a
     subsequent invocation of the umask utility.

     Assuming the mode mask is set as above, the command:

       umask g-w

     sets the mode mask so that subsequently created  files  have
     their S_IWGRP and S_IWOTH bits cleared.

     The command:

       umask --w

     sets the mode mask so that subsequently created  files  have
     all  their  write bits cleared. Notice that mask operands r,
     w, x, or anything beginning with a hyphen (-), must be  pre-
     ceded by - to keep it from being interpreted as an option.


ENVIRONMENT VARIABLES

     See environ(5) for descriptions of the following environment
     variables that affect the execution of umask:  LANG, LC_ALL,
     LC_COLLATELC_CTYPE, LC_MESSAGES, and NLSPATH.


EXIT STATUS

     The following exit values are returned:

     0     The file mode creation mask was successfully  changed,
           or no mask operand was supplied.

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User Commands                                            umask(1)

     >0    An error occurred.


ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

  /usr/bin/umask, csh, ksh, sh
     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|
    | Interface Stability         | Standard                    |
    |_____________________________|_____________________________|

  ksh93
     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|
    | Interface Stability         | External                    |
    |_____________________________|_____________________________|


SEE ALSO

     chmod(1),  csh(1),  ksh(1),   ksh93(1),   sh(1),   chmod(2),
     creat(2),  umask(2),  profile(4), attributes(5), environ(5),
     standards(5)

SunOS 5.11          Last change: 17 Sep 2007                    6


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