Change file permissions
chmod PERMISSIONS FILE
Applies PERMISSIONS to FILE
+PERMISSION Add PERMISSION (w=write, r=read, x=execute)-PERMISSION Remove PERMISSION (w=write, r=read, x=execute)TARGET+PERMISSION Add PERMISSION to TARGET (u=user/owner, g=group, o=others)TARGET-PERMISSION Remove PERMISSION from TARGET (u=user/owner, g=group, o=others)Add permission
chmod +w file.txt
Makes file.txt writable for everyone
Add permission for owner
chmod u+x file.txt
Makes file.txt executable for the owner
Remove permission
chmod -x file.txt
Removes execute permission for file.txt
Remove permission for other users
chmod o-r file.txt
Removes read access for other users
Standard file permissions
chmod 644 file.txt
Owner: read and write, others: read only
Make script executable
chmod 755 program
Owner: read, write, and execute, others: read and execute
Private file
chmod 600 secret.txt
Owner: read and write, others: no access