chmod: Symbolic Mode

The chmod command changes file permissions. In symbolic mode, you specify:

1. Who: u (user/owner), g (group), o (others), a (all)
2. Action: + (add), - (remove), = (set exactly)
3. Permission: r, w, x

Adding execute permission for the owner

chmod u+x script.sh

Now the owner can run script.sh as a program.

Removing write permission from group and others

chmod go-w secret.txt

Group and others can no longer modify this file.

Setting exact permissions

chmod u=rwx,g=rx,o=r file.txt

This sets owner to full access, group to read+execute, others to read only.

Multiple changes at once

chmod u+x,g-w file.txt

Add execute for user AND remove write for group in one command.

After each chmod, verify with ls -l to confirm the change took effect.

Mission: Activate the Firmware Deployer

A critical firmware update is ready in deploy.sh, but the script cannot run yet, and it also carries sensitive settings that outsiders should never read.

1. Give the owner permission to run deploy.sh as a program.
2. Remove read access from others on deploy.sh so outsiders cannot view it.
3. Confirm the changes by viewing the file's detailed permissions.
4. Create a folder called deploy-ready and copy deploy.sh into it.

Expected result

deploy.sh is executable by the owner and unreadable by others, and a copy sits in deploy-ready.