This document discusses Linux file permissions and commands used to modify permissions. It explains the rwx permissions for owner, group, and other using an example ls -l output. It then covers the chmod, chown, and chgrp commands to change file ownership, group, and permissions including recursive (-R) options and using symbolic modes.

1. Linux/Unix
-
2010, Spring

2. • (Owner)
• (Group)
• (Other)

3. Linux
littleq@ubuntu:~$ ls -l
drwxr-xr-x 3 littleq littleq 4096 2010-02-01 01:00 ~
drwx------ 2 littleq littleq 4096 2010-02-04 11:53 amsn_received
drwxr-xr-x 3 littleq littleq 4096 2010-02-21 17:33 Downloads
drwxr-xr-x 9 root root 4096 2010-02-20 23:24 judge
drwx------ 2 littleq littleq 4096 2010-01-25 17:22 mail
drwxr-xr-x 8 littleq littleq 4096 2010-02-18 16:28 OnlineJudge
drwxr-xr-x 4 littleq littleq 4096 2010-03-08 16:47 program
drwxr-xr-x 7 littleq littleq 4096 2010-03-08 22:42 public_html
drwxr-xr-x 3 math11 mathlab 4096 2010-02-21 17:33 Downloads

4. Read Write eXecute
R W X
4 2 1

5. Linux
4 2 1 4 x 1 4 x 1
d r w x r - x r - x
7 5 5

6. • chmod: SUID...
• chown:
• chgrp:

7. chmod-
• chmod 775 < >
rwxrwxr-x
4 2 1 4 2 1 4 0 1
7 7 5
• chmod a+w,g+w < >
u
+ W
g
- R
o = X
a

8. chown-
• chown [-R] < >[: ] < >
• chown -R monkey:mathlab banana
• chown littleq aicp0529

9. chgrp-
• chgrp < > < >
• chgrp mathlab yellowfish

10. • •
ASCII
binary •
data
•
•
•
block
character