Use the cmod command to set file permissions.
The chmod command uses a three-digit code as an argument.
The three digits of the chmod code set permissions for these groups in this order:
- Owner (you)
- Group (a group of other users that you set up)
- World (anyone else browsing around on the file system)
Each digit of this code sets permissions for one of these groups as follows. Read is 4. Write is 2. Execute is 1.
The sums of these numbers give combinations of these permissions:
0 = no permissions whatsoever; this person cannot read, write, or execute the file
1 = execute only
2 = write only
3 = write and execute (1+2)
4 = read only
5 = read and execute (4+1)
6 = read and write (4+2)
7 = read and write and execute (4+2+1)
Chmod commands on file aathith.txt (use wildcards to include more files)
| Command | Purpose |
|---|---|
| chmod 700 aathith.txt | Only you can read, write to, or execute aathith.txt |
| chmod 777 aathith.txt | Everybody can read, write to, or execute aathith.txt |
| chmod 744 aathith.txt | Only you can read, write to, or execute aathith.txt Everybody can read aathith.txt; |
| chmod 444 aathith.txt | You can only read aathith.txt, as everyone else. |
You can use the ls command with the -l option to show the file permissions set. For example, for aathith.txt, I can do this:
$ ls -l aathith.txt
-rwxr--r-- 1 december december 81 Feb 12 12:45 aathith.txt
The sequence -rwxr--r-- tells the permissions set for the file aathith.txt.
- The first
-tells thataathith.txtis a file. - The next three letters,
rwx, show that the owner has read, write, and execute permissions. - Then the next three symbols,
r--, show that the group permissions are read only. - The final three symbols,
r--, show that the world permissions are read only.
Disclaimer: This post is copied from this link, I have created it here just for my reference.