UNIX Basic commands: chmod

The chmod command changes the access mode of one file or multiple files.

The syntax for the chmod command is:

chmod [option] mode files

options:

-R	Descend directory arguments recursively while setting modes.
-f	Suppress error messages if command fails.

mode:

Who	u=user, g=group, o=other, a=all (default)
Opcode	+ means add permission - means remove permission = means assign permission and remove the permission of unspecified fields
Permission	r=Read, w=write, x=Execute, s=set uid bit, t=sticky bit u=user, g=group, o=other, l=mandatory locking

Examples:

chmod 751 tech
chmod u=rwx, g=rx, o=x tech
chmod =r tech

* Please note that there are many flavors of UNIX, so if in doubt, consult your man pages.