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Lab04EXTRALinuxFilePerms
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useradd [name]- adds a user with that username -
passwd [username]- changes the password of that user -
groupadd [name]- makes a group with that name -
usermod -aG [groupname] [username]- adds the user specified to the specified group -
mkdir /[name]- makes a directory with that name
I made 3 new users, Fred, Bob, and Alice, and 2 new groups, Marketing and Management
- Fred and Bob are in Marketing
- Alice is in Management
After exploring the default permissions, I needed to change the /marketing directory to be in the Marketing group. To do this I used:
chgrp marketing /marketing - applies the "marketing" group to the "/marketing" directory
Then I needed to give write permission to the group for the directory, which I did with the following command:
chmod g+w /marketing
To trim off the permissions of everyone else for this directory, I used the command: chmod o-rwx /marketing (the o means other)
To trim the read permissions of all the files in the current directory use: chmod o-r *
- r - 100 - 4
- w - 010 - 2
- x - 001 - 1
600 = rw-------
- This is essentially 4+2+(0x7) because r represents 4 and w represents 2
777 = rwxrwxrwx
- Bad Idea
666 = rw-rw-rw- 640 = rw-r-----
- The one I used in the lab most commonly, rw for user, r for group, nothing for everyone
chmod -v 600 [filename] - filename permissions changed to rw-------
- Syntax for using the Octal numbers to change file permissions (I like this better)
chmod u+rw,g-rwx,o-rwx [filename] - same as previous, assuming user did not already have x perms
https://www.redhat.com/sysadmin/linux-file-permissions-explained