Did You Know? that you can that you can source /dev/urandom to randomly generate your secure password? For example to generate 6 characters long password you could: # head -c 6 /dev/urandom | mimencode - this will generate 6 random characters NOTE: - mimencode is part of metamail package
-e, --expiredate EXPIRE_DATE The date on which the user account will be disabled. The date is specified in the format YYYY-MM-DD. -L, --lock Lock a user’s password. This puts a ’!’ in front of the encrypted password, effectively disabling the password. You can’t use this option with -p or -U. -U, --unlock Unlock a user’s password. This removes the ’!’ in front of the encrypted password. You can’t use this option with -p or -L.
4. Examples
Lets see how we can lock account for user linuxconfig. This will add "!" into /etc/shadow for user linuxconfig. NOTE: this command requires superusers privileges.
# usermod -L linuxcofnig
Now we can try login with user linuxconfig and see if that works:
With a -U option we can unlock account:
# usermod -U linuxcofnig
Check if the "!" is removed from etc/shadow:
# grep linuxconfig etc/shadow | head -c 15 | sed -e 's/$/\n/'
To make account expire we can use --expiredate option. This will expire user account on 1 January 2010.