Linux file permissions
Commands:
- chmod - Changes access permissions to files/directories
- chown - Changes user and/or group ownership of files/directories
- chgrp - Changes group ownership of files/directories
Examples:
- To change the permissions of the directory some-directory to 777:
- chmod 777 some-directory
- To change the user ownership of the directory some-directory to user1:
- chown user1 some-directory
- To change the group ownership of the directory some-directory to group1:
- chgrp group1 some-directory
Tips:
- By adding a colon after the user, chown can be used to change the group and user ownership simultaneously, for example:
- chown user1:group1 some-directory
- The above commands can use -R to recursively change any sub-directories and their contents, for example:
- chmod 777 -R some-directory/
Access permissions:
Permissions are allocated for three separate groups:
- User: owner of the file
- Group: group owner of the file
- Others: other users not in the group
These are then given permissions, e.g:
- 644:
- Owner can: Read and Write
- Group can: Read
- Others can: Read
- 775:
- Owner can: Read, Write and Execute
- Group can: Read, Write and Execute
- Others can: Read and Execute
- See the table below for a full list:
| No. |
Read (r) |
Write (w) |
Execute (x) |
| 0 |
Denied |
Denied |
Denied |
| 1 |
Denied |
Denied |
Allowed |
| 2 |
Denied |
Allowed |
Denied |
| 3 |
Denied |
Allowed |
Allowed |
| 4 |
Allowed |
Denied |
Denied |
| 5 |
Allowed |
Denied |
Allowed |
| 6 |
Allowed |
Allowed |
Denied |
| 7 |
Allowed |
Allowed |
Allowed |
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