OSXFAQ Daily Unix Tricks  

Week 47 - Shell Built-ins (9 June 2003)

by Adrian Mayo - Senior Editor for Mac OS X Unix

Wednesday - umask

The umask built-in command tells the file system the default permissions to apply to newly created files and directories. The umask can be set in your tcsh startup file, or applied just to a partiaular Terminal session.

Without a 'umask' directories are set to:

and files to:

The umask is usually set to 022:

% umask 022
% touch test-file
% ls -al test-file
-rw-r--r--   1 saruman  staff           0 Jun  9 11:22 test-file

Give write access to your group:

% rm test-file
% umask 002
% touch test-file
% ls -al test-file
-rw-rw-r--   1 saruman  staff           0 Jun  9 11:23 test-file

For shared files:

% rm test-file
% umask 000
% touch test-file
% ls -al test-file
-rw-rw-rw-   1 saruman  staff           0 Jun  9 11:23 test-file

For private files:

% rm test-file
% umask 077
% touch test-file
% ls -al test-file
-rw-------   1 saruman  staff           0 Jun  9 11:23 test-file

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