title: Chmod date: 2021-07-01 10:51:44 background: bg-emerald-600 tags: - permission categories: - Linux Command intro: |
```shell script
$ chmod [options]
#### Example
```shell
$ chmod 755 foo.txt
$ chmod +x quickref.py
$ chmod u-x quickref.py
$ chmod u=rwx,g=rx,o= quickref.sh
$ chmod -R 755 my_directory
The chmod
command stands for "change mode"
Chmod Generator allows you to quickly and visually generate permissions in numerical and symbolic.
Command | s | Meaning |
---|---|---|
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
Permission | Description | Octal | Decimal |
---|---|---|---|
--- |
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) |
{.show-header}
Who (abbr.) | Meaning |
---|---|
u |
U ser |
g |
G roup |
o |
O thers |
a |
A ll, same as ugo |
{.show-header}
Abbreviation | Permission | Value |
---|---|---|
r |
R ead |
4 |
w |
W rite |
2 |
x |
Ex ecute |
1 |
- |
No permission | 0 |
{.show-header}
Abbreviation | File Type |
---|---|
d |
D irectory |
- |
Regular file |
l |
Symbolic L ink |
{.show-header}
Symbol | Description |
---|---|
+ |
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
```shell script \( chmod 700 ~/.ssh \) chmod 600 ~/.ssh/authorized_keys \( chmod 600 ~/.ssh/id_rsa \) chmod 600 ~/.ssh/id_rsa.pub $ chmod 400 /path/to/access_key.pem
### Web Permissions
```shell script
$ 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 {} \;
script
$ chmod -R 644 /your_path
$ find /path -type d -exec chmod 755 {} \;
$ find /path -type f -exec chmod 644 {} \;
See: Command Substitution