Quick Start Guide

Execute—executing les or changing to the directory

Setuid bit—the application or program is started as if it were started by the

owner of the le

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 rst digit sets the set user ID (SUID) (4), the set group ID (2), and the

sticky (1) bits. The second digit denes the permissions of the owner of the le.

The third digit denes the permissions of the group members and the last digit

sets the permissions for all other users. The read permission is set with 4, the

write permission with 2, and the permission for executing a le is set with 1. The

owner of a le would usually receive a 6 or a 7 for executable les.

gzip [parameters] files

This program compresses the contents of les 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 les or even entire

directories, use the tar command.

-d

Decompresses the packed gzip les 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 les 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 le and not to the screen as is usually the case

-c

Creates a new tar archive

-r

Adds les to an existing archive

-t

Outputs the contents of an archive

-u

Adds les, but only if they are newer than the les already contained in the