Bash — Permissions

Permission types

Permission	Symbol	Numeric
Read	r	4
Write	w	2
Execute	x	1

Viewing permissions

ls -la
# -rw-r--r-- 1 user group 1234 Aug 23 10:00 file.txt
#  ^^^^^^^^
#  Owner Group Others

Changing permissions

chmod +x script.sh      # Add execute
chmod -w file.txt       # Remove write
chmod u+w file.txt      # Add write for user
chmod g+r file.txt      # Add read for group
chmod o-x file.txt      # Remove execute for others

Numeric permissions

chmod 755 script.sh     # rwxr-xr-x
chmod 644 file.txt      # rw-r--r--
chmod 700 private.sh    # rwx------
chmod 666 public.txt    # rw-rw-rw-
chmod 777 everything.sh # rwxrwxrwx

Ownership

chown user:group file    # Change owner
chown -R user:group dir  # Recursive
chgrp group file         # Change group only

Special permissions

chmod u+s program        # Setuid
chmod g+s directory      # Setgid
chmod +t directory       # Sticky bit

Mini Practice

Write Bash code that:

1. Views file permissions
2. Changes permissions with symbolic mode
3. Changes permissions with numeric mode
4. Changes file ownership

Up Next

In the next lesson, you'll learn about Processes — managing processes in Bash.