User, group and permission overview

PHOTO EMBED

Mon Jun 21 2021 20:32:43 GMT+0000 (Coordinated Universal Time)

Saved by @dphillips #authentification #permissions #group

# Check if 'webmasters' group exist
cat /etc/group | grep webmasters

# Create 'webmasters' group
sudo addgroup webmasters

# Add users to 'webmasters' group
sudo usermod -a -G webmasters username

# INFO: Group assignment changes won't take effect until the users log out and back in.

# Change group owner of the directory to webmaster user
sudo chgrp -R webmasters /etc/nginx/
  
# Give write permission to the group
sudo chmod -R g+w /etc/nginx/
  
# Create file as different user
sudo -u username touch /etc/nginx/test.txt


# When using a number mask for permission representation there are only a few basic permissions

4: Read
2: Write
1: Execute

# Combined you get this table

+-----+---+--------------------------+
| rwx | 7 | read    write   execute  |
| rw- | 6 | read    write            |
| r-x | 5 | read            execute  |
| r-- | 4 | read                     |
| -wx | 3 |         write   execute  |
| -w- | 2 |         write            |
| --x | 1 |                 execute  |
| --- | 0 |                          |
+------------------------------------+
  
# The permissions for user, group and other are listet after each other when looking them up

+------------+------+-------+
| Permission | Octal| Field |
+------------+------+-------+
| rwx------  | 700  | User  |
| ---rwx---  | 070  | Group |
| ------rwx  | 007  | Other |
+------------+------+-------+
  
# This boils down to this
  
+------------------------+-----------+--------------------------------------+
| chmod u=rwx,g=rwx,o=rx | chmod 775 | For world readable directories		|
|                        |           |   Members of group can change files	|
| chmod u=rwx,g=rx,o=    | chmod 750 | For group readable directories		|
|                        |           |   Members of group can change files	|
| chmod u=rwx,go=        | chmod 700 | For private direcories				|
+------------------------+-----------+--------------------------------------+
content_copyCOPY

https://askubuntu.com/questions/488485/allowing-a-group-read-write-access-to-a-directory