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 symbolicmode 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 symbolicmode string.
In a symbolicmode 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 SIWOTH 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 SIWGRP and SIWOTH 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, LCAL,
LCOLATELCTYPE, LCMESAGES, 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.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
/usr/bin/umask, csh, ksh, sh
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
Interface Stability Standard
ksh93
ATRIBUTE TYPE ATRIBUTE 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)
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