Chmod cheat sheet

chmodCheatSheet.md

Chmod codes cheat sheet

How to use chmod codes in UNIX:

1. There are three types of permisions in files and folders in unix
   1. Read (r)
   2. Write (w)
   3. Execute (x)
2. And, there is a clasificacion of users called UGO (explained bellow):
   1. U ~> User (usually, you)
   2. G ~> Group (eg sudo group)
   3. O ~> Others

When you run $ ls -l your output will be something like this:

-rwxrwxrwx@  1 user  staff  708301983 Aug 11 13:51 all.zip
-rw-r--r--   1 user  staff          0 Aug 22 22:10 chmodCheatSheet.md
-r--------@  1 user  admin       1692 Jul  6 10:13 deploykey.pem
drwxr-xr-x   3 user  staff        102 Aug 20 19:14 deploynode

How to read this?

Where is a letter put a 1 and where is a - put a 0. Examples:

U	G	O
r w x	r w x	r w x
1 1 1	1 1 1	1 1 1

So, user, group and others can read, write and excute the file or folder

U	G	O
r w -	r --	r - x
1 1 0	1 0 0	1 0 1

So, user can read and write, group can only read, finally other can read and execute

As you can see, we can play with these permissions

U	G	O
r - x	r w -	- - -
1 0 1	1 1 0	0 0 0
U	G	O
- w x	r - x	- - x
0 1 1	1 0 1	0 0 1

Finally, the codes! (sorry)

Bin	Decimal	Representation
000	0	- - -
001	1	- - x
010	2	- w -
011	3	- w x
100	4	r - -
101	5	r - x
110	6	r w -
111	7	r w x

The sintax is something like this: $ chmod u/permissions g/permissions o/permissions file[or /dir/]

• So, if I run $ chmod 777 file <=> rwx rwx rwx everybody can do anything with file
• Or I run $ chmod 744 dir <=> rwx r-- r--only user can read, write and execute, group and others only read dir.
• Or run $ chmod 200 file2 <=> -w- --- ---only you can write file2

Thanks for reading, I hope it works! Follow me on Twita and GitHub

Refs:

1. http://www.pa.msu.edu/~abdo/unixcc.html
2. http://www.yourownlinux.com/2013/09/chmod-basics-of-filesdirectories.html