permissions

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permissions
In Linux, files and directories are owned by a user and a group (see File Ownership). On top of that, this user, group, and other ones (groups and users), have different permissions on these files. That's what we call file permissions.
You might need to change them.
If this can be boring to new users, remember that this is a huge part of what makes Linux as secured as it is, and you are required to know this if you wish to do anything serious with Linux.
Check current permissions
Check permissions from a file or all files of any directory
ls -al /path/to/file/or/dir
Sample output:
1
[email protected]:~$ ls -al twserver
2
-rwxr-x--- 1 ultimatebyte ultimatebyte 5691 Jan 30 01:14 twserver
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Explaination:
First character is a a - for files, or a d for directories
Three next ones are owner permissions: rwx
Three next ones are group permissions: rwx
Three next ones are "others permissions: rwx for groups and users that are now owning the file
First user listed is the owner
Next entry is the group owning the file
"r" stands for "read", "w" stands for "write", "x" stands for execute.
If any letter from rwx is showed as a -, it means that the permission is not granted.
Change permissions
Change permissions from files or directories
Command
chmod
Recursive syntax (include sub files and directories)
Append -R to your chmod
chmod -R
Syntax 1)
Set all permissions at once
chmod 777 == chmod -a+rwx
chmod 000 == chmod -a-rwx
First number is for user, second is for group, third for others
Values
1
0 no permissions
2
1 x
3
2 w
4
3 wx
5
4 r
6
5 rx
7
6 rw
8
7 rwx
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Example
Default permissions are 755. If you wish to prevent other users from interacting with your files, then 750 can be great.
chmod -R 750 /home/userdir
Syntax 2)
We used rwx for these, but of course, you should pick the permissions you wish to add or remove.
Permissions add
chmod +rwx filename
Will add read, write, and execute permissions to this file anyone on the machine. r stands for "read", w for "write", and x for "execute"
Example : chmod +x filename
Will make the file executable by anyone on the machine.
Permissions remove
chmod -rwx filename Will remove read, write, and execute permissions to this file anyone on the machine.
Note : root user is the only exception.
Permissions for user/group/others/all
chmod -u+rwx
chmod -g+rwx
chmod -o+rwx
chmod -a+rwx
Multiple permissions at once
chmod -u+r,g-w,o-rwx
Of course, you can replace +rwx by anything previously mentioned
Set GUID and GID
Advanced permissions management, you will likely not need this for game servers.
Set GUID
No GUID
chmod -R a-s /path/to/dir
chmod -R 0xxx /path/to/dir
Example : chmod -R 0640 /home/user/website
Set UID
Files will run as the user
chmod -R u+s /path/to/dir/
chmod -R 2xxx /path/to/dir
Set GID
Any subdir and subfile will have the same group
chmod -R g+s /path/to/dir/
chmod -R 4xxx /path/to/dir
Set GUID
Set both UID and GID
chmod -R a+s /path/to/dir/
chmod -R 6xxx /path/to/dir
network-interfaces
Troubleshooting
Last modified 2yr ago
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Contents
Check current permissions
Check permissions from a file or all files of any directory