When I forgot password...

Password! I have lots of machines to manage, and passwords to remember. Therefore sometimes I can not remember a password when I login to a machine. There are some simple methods to remember, for example I can write the password on a notebook. Even though that, I still forgot. As a result, I have to reset the password! On linux (Ubuntu 14.04), it's simple:

1. Reboot to GRUB and rescure, select root( drop to shell prompt)
2. RE-mount filesystem to r/w mode: # mount -o remount,rw /
3. Change the password: # password username

When I'm lazy to type password

Typing ssh user@hostname and then password is quite normal in my daliy life. I think it may cost at least half a hour per day to type these long, complex, hard-remember password again and again. As said that lazy is good for programmer, I decide to change something! (Also because I installed Ansible to manage lots of machines) Using ssh without typing password! It's simple, too:

0. login to control machine and type following commands to generate a key and give it to other machines
1. $ ssh-keygen
2. $ ssh-copy-id -i ~/.ssh/ user@remote_machine

Type the password of user@remote_machine last time! Then, ssh user@remote_machine will be simple!

NO password when sudo

I've already write this in the previous post, but some changed in this one. It's not safe for a normal user to do root's matters. As result, there is sudo. But in some cases, the password is not necessary. For example, using ansible. We can cancel the verification by doing this:

1. change sudo setting in normal user or root: `#/$ pkexec visudo`
# change the %sudo line into following:

then exit and enjoy no password for sudo xxx.