LINUX file permissions

from www.linuxforums.org/security/file_permissions.html

r readable
w writable
x executable

u user
g group - ie Administrators
0 others - not a member of a group or the owner of the file
a all
- no permission

use ls -l to see file permissions

eg

ls -l myfile
-rwxr-x--- 1 george administrators 10 2006-03-09 21:31 myfile

so for george - the owner - the file is readable , writable and executable.
for other administrators - the file is only readable - not writable but still executable
other users cannot read, write or run this file.

changing permissions : chmod
if george wanted to give write permission tot he other administrators
he would type

chmod g+w myfile

see the url for details