Vim mode in Bash

Reference to Arabesque

Because the Bash shell uses GNU Readline, you’re able to set options in .bashrc and .inputrc to extensively customise how you enter your command lines, including specifying whether you want the default Emacs-like keybindings (e.g. Ctrl+W to erase a word), or bindings using a modal interface familiar to vim users.

set editing-mode vi

If you only wnat to use this mode in Bash, an alternative is to use the following in your .bashrc, again with a login/logout or resourcing of the file:

set -o vi

You can check this has applied correctly with the following, which will spit out a list of the currently available bindings for a set of fixed possible actions for text:

$ bind -P

The other possible value fo editing-mode is **emacs. Both option simply change settings in the output of bind -P above.

This done, you should find that you open a command line in insert mode, but when you press Escape or Ctrl+[, you will enter an emulation of Vim’s normal mode. Enter will run the command in its present state while in either mode. The bindings of most use in this mode are the classic keys for moving to positions on a line:

^ - Move to start of line
$ - Move to end of lin
b - Move back a word
w - Move forward a word
e - Move to the end of the next word

powerline-shell

Solve Ubuntu: Sudo Unable to Resolve Host

Edit: /etc/hosts

# Add the codes below to /etc/hosts
127.0.0.1   `Your host name`

Add and Delte Users on Ubuntu

Reference to digitalocean

Introduction

One of the most basic tasks to that you should know how to do on a fresh Linux server is add and remove users. When you create a new server, you are only given the root account by default.

While this gives you a lot of powe and flexibility, it is also dangerous and can be destructive. It is almost always a better idea to add an additional, unprivileged user to do common tasks. You also should create additional accounts for any other users you may have on your system. Each user should have a different account.

You can still acquire administrator privileges when you need them through a mechanism called sudo. In this guide we will cover how to create user accounts, assign sudo privileges, and delete users.

How To Add a User

If you are signed in as the root user, you can create a new user at any time by typing:

adduser **newuser**

If you are signed in as a non-root uer who has been given sudo privileges, as demonstrated in the initial server setup guide, you can add a new user by typing:

sudo adduser newuser

either way, you will be asked a series of questions. The procedure will be:

* Assign and confirm a password for new user

* Enter any additional information about the new user. This is entirely
  optional and can be skipped by hitting "ENTER" if you don't wish to
  utilize these fields.

* Finally, you'll be asked to confirm that the information you provided was
  correct. Type "Y" to continue.

Your new user is now ready for use! You can now log in using the password you set up.

Note: Continue on if you need your new user to have access to administrative functionality.

How To Grant a User Sudo Privileges

If your new user should have the ability to execute commands with root (administrative) privileges, you will need to give the new user access to sudo.

We can do this by using the visudo command, which opens the appropriate configuration file in your editor. This is the safest way to make these changes.

If you are currently signed in as the root user, type:

visudo

If you are signed in using a non-root user with sudo privileges, type:

sudo visudo

Search for the line that looks like this:

root    ALL=(ALL:ALL) ALL

Below this line, copy the format you see here, changing only the word “root” to reference the new user that you would like to give sudo privileges to:

root    ALL=(ALL:ALL) ALL
**newuser** ALL+(ALL:ALL) ALL

You should add a new line like this for each user that should be given full sudo privileges. When you are finished, you can save and close the file by hitting CTRL-X, followed by “Y”, and then hit “ENTER” to confirm.

Now, your new user is able to execute commands with administrative privileges.

When signed in as the new user, you can execute commands ad your regular user by typing commands as normal:

some_command

You can execute the same command with administrative privileges by typing sudo ahead of the command:

sudo some_command

You will be prompted to enter the password of the regular user account you are signed in as.

How To Delete a User

In the event that you no longer need a user, it is best to delete the old account. You can delete the user itself, without deleting any of his or her files by typing this as root:

deluser **newuser**

If you are signed in as another non-root user with sudo privileges, you could instead type:

sudo deluser newuser

If, instead, you want to delete the user’s home directory when the user is deleted, you can issue the following command as root:

deluser --remove-home newuser

If you’re rnning this as a non-root user with sudo privileges, you would instead type:

sudo deluser --remove-home newuser

If you had previously configured sudo privileges for the user you deleted, you may want to remove the relevant line again by typing:

visudo

Or use this if you are a non-root user with sudo privileges:

sudo visudo



root    ALL=(ALL:ALL) ALL
newuser ALL=(ALL:ALL) ALL   # DELETE THIS LINE

This will prevent a new user created with the same name from being accidentally given sudo privileges.

Conclusion

You should now have a fairly good handle on how to add and remove users from your Ubuntu system. Effective user management will allow you separate users and give them only access that they are required to do their job.

For more information about how to configure sudo, check out our guide on how to edit the sudoers file here.