umask(1) User Commands umask(1)NAMEumask - get or set the file mode creation mask
SYNOPSIS
/usr/bin/umask [-S] [mask]
sh
umask [ooo]
csh
umask [ooo]
ksh
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 subse‐
quently 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 . -execumask ...
it does not affect the file mode creation mask of the caller's environ‐
ment. 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 creation mask to standard
output.
sh
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'' speci‐
fied by the system for the creation of a file (see creat(2)). For exam‐
ple, 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).
· If ooo is omitted, the current value of the mask is printed.
· umask is recognized and executed by the shell.
· 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 complement of the previous umask value. If mask is
omitted, the current value of the mask is printed.
OPTIONS
The following option is supported:
-S Produces symbolic output.
The default output style is unspecified, but will be recognized on a
subsequent invocation of umask on the same system as a mask operand to
restore the previous file mode creation mask.
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 cre‐
ation mask is the logical complement of the file permission
bits portion of the file mode specified by the symbolic_mode
string.
In a symbolic_mode value, the permissions op characters + 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 per‐
missions 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 recognized as a mask oper‐
and. The use of an operand obtained in this way is not obso‐
lescent, 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 oper‐
and.
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 creation 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 commands, the
umask command can be used to write the current value of the mode mask:
example$ umask
0002
The output format is unspecified, but historical implementations 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 preceded 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.
>0 An error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOchmod(1), csh(1), ksh(1), sh(1), chmod(2), creat(2), umask(2), pro‐
file(4), attributes(5), environ(5), standards(5)SunOS 5.10 23 Jun 2005 umask(1)
