# Linux users/groups/permissions cheatsheet
See a file's ownership and permissions with `ls -a`

## Add user
```
$ sudo useradd -m peter
$ sudo passwd peter

$ groupadd myAppUsers

$ sudo usermod -a -G peter myAppUsers
```

`adduser` and `addgroup` are interactive convenience scripts that wrap the `useradd` and `groupadd` commands.

## Get information about a user, including the user's group memberships
```
$ id
$ id peter
```

## List groups
```
$ groups
$ groups peter
```

## File permissions
List files, showing permissions and ownership information
```
ls -l
```

Permissions are course grained, and set for exactly 3 scopes: owner, groups and others (global)
```
chmod u=rwx,g=rwx,o=rwx myFile.txt
chmod 777 myFile.txt
```

TODO: `setfacl` - for working with ACLs

## Change ownership of a file
```
$ chown peter myFile.txt
$ chgrp myAppUsers myFile.txt
```

## Execute a command with elevated rights elevated
```
$ sudo commandname
```

su - switch user