id is used to display information about a user getting information for the current user getting information for specific user getting the user ID for specific user getting the group ID for specific user getting the name for a specific user getting all groups for a specific user
chmod changes the permissions of a file or a directory only the owner or the superuser is allowed to do that youcan change the permissions with 2 ways 1 → by symbolic representation symbolic representation example 2 → by octal number representation octal number representation example
chmod symbolic representations explanation u → owner g → group o → others → add permission - → remove permission = → set permissions
r → readable w → writable x → executable s → set user id S → set group id u+rwx → add to the owner read, write and execute permissions g-wx → removes from the group write and execute permissions o=rx → set for the others read and execute permissions
chmod octal number representation there are 3 digits, like 644 1st → for the owner(u) 2nd → for the group(g) 3rd → for the other(o) 0 → no permissions(---) 1 → execute permission(--x) 2 → write permission(-w-) 3 → write and execute permissions(-wx) 4 → read permission(r--) 5 → read and execute permissions(r-x) 6 → read and write permissions(rw-) 7 → read, write and execute permissions(rwx) sets 640 → read and execute for the owner, read permissions for the group and no permissions for the rest
umask determines the default permissions applied to new files/directories gets the current default permission chaging to 0000, no file or directory will have any restrictive permissions by default changing back to 0022 to understand the new permission just subtract files 666-022 = 644 directories 777-022=755 echo "umask new_mask" →→ ~/.bashrc → adds a new mask to .bashrc and you it will be permanent