This quick reference cheat sheet provides a brief overview of file permissions, and the operation of the chmod.
$ chmod [options] <permissions> <file>
$ chmod 755 foo.txt
$ chmod +x ref.softcrony.py
$ chmod u-x ref.softcrony.py
$ chmod u=rwx,g=rx,o= ref.softcrony.sh
$ chmod -R 755 my_directory
The chmod command stands for "change mode"
Read — — —
Write — — —
Execute — — —
Chmod Generator allows you to quickly and visually generate permissions in numerical and symbolic.
400 — r-------- — Readable by owner only
500 — r-x------ — Avoid Changing
600 — rw------- — Changeable by user
644 — rw-r--r-- — Read and change by user
660 — rw-rw---- — Changeable by user and group
700 — rwx------ — Only user has full access
755 — rwxr-xr-x — Only changeable by user
775 — rwxrwxr-x — Sharing mode for a group
777 — rwxrwxrwx — Everybody can do everything
$ ls -l
-rw-r--r-- 1 root root 3 Jun 29 15:35 a.log
drwxr-xr-x 2 root root 2 Jun 30 18:06 dir
d rwx r-x r-x
┬ ─┬─ ─┬─ ─┬─
│ │ │ │
│ │ │ └─ 4. Other｜5 (4+0+1)
│ │ └────── 3. Group｜5 (4+0+1)
│ └─────────── 2. User ｜7 (4+2+1)
└─────────────── 1. File Type | directory
--- — No Permission — 000 — 0 (0+0+0)
--x — Execute — 001 — 1 (0+0+1)
-w- — Write — 010 — 2 (0+2+0)
-wx — Execute and Write — 011 — 3 (0+2+1)
r-- — Read — 100 — 4 (4+0+0)
r-x — Read and Execute — 101 — 5 (4+0+1)
rw- — Read and Write — 110 — 6 (4+2+0)
rwx — Read, Write and Execute — 111 — 7 (4+2+1)
u — User
g — Group
o — Others
a — All, same as ugo
r — Read — 4
w — Write — 2
x — Execute — 1
- — No permission — 0
d — Directory
- — Regular file
l — Symbolic Link
+ — Add
- — Remove
= — Set
$ chmod 600 example.txt
$ chmod u=rw,g=,o= example.txt
$ chmod a+rwx,u-x,g-rwx,o-rwx example.txt
$ chmod 664 example.txt
$ chmod u=rw,g=rw,o=r example.txt
$ chmod a+rwx,u-x,g-x,o-wx example.txt
$ chmod 777 example.txt
$ chmod u=rwx,g=rwx,o=rwx example.txt
$ chmod a=rwx example.txt
Deny execute permission to everyone.
$ chmod a-x chmodExampleFile.txt
Allow read permission to everyone.
$ chmod a+r chmodExampleFile.txt
Make a file readable and writable by the group and others.
$ chmod go+rw chmodExampleFile.txt
Make a shell script executable by the user/owner.
$ chmod u+x chmodExampleScript.sh
Allow everyone to read, write, and execute the file and turn on the set group-ID.
$ chmod =rwx,g+s chmodExampleScript.sh
In order to remove read write permissions given to a file, use the following syntax:
$ chmod o-rw example.txt
For our file example.txt, we can remove read write permissions using chmod for group by running the following command:
$ chmod g-rx example.txt
To remove chmod read write permissions from the group while adding read write permission to public/others, we can use the following command:
$ chmod g-rx, o+rx example.txt
But, if you wish to remove all permissions for group and others, you can do so using the go= instead:
$ chmod go= example.txt
$ chmod +x ~/example.py
$ chmod u+x ~/example.py
$ chmod a+x ~/example.py
$ chmod 754 foo.sh
$ chmod u=rwx,g=rx,o=r foo.sh
$ chmod 700 ~/.ssh
$ chmod 600 ~/.ssh/authorized_keys
$ chmod 600 ~/.ssh/id_rsa
$ chmod 600 ~/.ssh/id_rsa.pub
$ chmod 400 /path/to/access_key.pem
$ chmod -R 644 /var/www/html/
$ chmod 644 .htaccess
$ chmod 644 robots.txt
$ chmod 755 /var/www/uploads/
$ find /var/www/html -type d -exec chmod 755 {} \;
$ chmod -R 644 /your_path
$ find /path -type d -exec chmod 755 {} \;
$ find /path -type f -exec chmod 644 {} \;
See: Command Substitution