Introduction

Once again, remember what sets off "the hitch-hikers guide to the galaxy" from "the encyclopedia Galactica": It has, written on its top, the phrase: Don't Panic!

Users

/etc/passwd

/etc/shadow

/etc/shadow (Cont.)

Groups

/etc/group

Users, Groups and Files

The File's Owner User

File Access Permissions

File Access Permissions - Who may access?

File Access Permissions - permission to do what?

Directory Access Permissions - permission to do what?

Access Permission scenarios

'read' Permission To Everyone On A File

'execute' Permission To Everyone On A File in ~/bin

'read' Permission To A Selected Group Of Users, On A File

'read' Permission To Everyone except a Group of Users

Users and Processes

Listing The Running Processes

Listing The Running Processes - Wider Format

Listing The Running Processes - Variations

Controlling Processes

Processes And Files

Which Processes Hold A File Open? (fuser)

Which Processes Hold A File Open? (fuser, Cont.)

Which Files Are Open By A Given Process? (lsof)

Which Files Are Open By A Given Process? (lsof, Cont.)

Default Permissions For New Files

The umask Command

The Octal Notation Of Access Permissions

The Octal Notation Of Access Permissions (Cont.)

The Octal Notation And umask

Special Access Permission Flags

The "Set User-ID" Flag

The "Set Group-ID" Flag

The "Sticky" Flag

Symbolic Links

A Symbolic Link Example

Symbolic Links Semantics

Permissions And Symbolic Links

What We Did NOT Cover Today

Google for them all on your spare time...

Originally written by Valid HTML 4.01!guy keren