Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 04-08-2006 Installation Manual page 365

As an alternative, a numeric code can be used. The four digits of this code are
composed of the sum of the values 4, 2, and 1—the decimal result of a binary mask.
The first digit sets the set user ID (SUID) (4), the set group ID (2), and the sticky
(1) bits. The second digit defines the permissions of the owner of the file. The third
digit defines the permissions of the group members and the last digit sets the per-
missions for all other users. The read permission is set with 4, the write permission
with 2, and the permission for executing a file is set with 1. The owner of a file
would usually receive a 6 or a 7 for executable files.
gzip [parameters] files
This program compresses the contents of files using complex mathematical algo-
rithms. Files compressed in this way are given the extension .gz and need to be
uncompressed before they can be used. To compress several files or even entire
directories, use the tar command.
-d
Decompresses the packed gzip files so they return to their original size and
can be processed normally (like the command gunzip)
tar options archive files
tar puts one or more files into an archive. Compression is optional. tar is a quite
complex command with a number of options available. The most frequently used
options are:
-f
Writes the output to a file and not to the screen as is usually the case
-c
Creates a new tar archive
-r
Adds files to an existing archive
-t
Outputs the contents of an archive
-u
Adds files, but only if they are newer than the files already contained in the
archive
Working with the Shell 365