zsh (“zee shell”) is awesome. Alas, its still not installed by default in most Linux distributions. Here’s how to install & configure zsh on Debian 9:
grokman@li598-26:~$ sudo apt-get update
[sudo] password for grokman:
Ign:1 http://mirrors.linode.com/debian stretch InRelease
Get:2 http://mirrors.linode.com/debian-security stretch/updates InRelease [94.3 kB]
Get:3 http://mirrors.linode.com/debian stretch-updates InRelease [91.0 kB]
Hit:4 http://mirrors.linode.com/debian stretch Release
Fetched 185 kB in 0s (434 kB/s)
Reading package lists... Done
grokman@li598-26:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
grokman@li598-26:~$ sudo apt-get install zsh
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
zsh-common
Suggested packages:
zsh-doc
The following NEW packages will be installed:
zsh zsh-common
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 4,270 kB of archives.
After this operation, 15.2 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Get:1 http://mirrors.linode.com/debian stretch/main amd64 zsh-common all 5.3.1-4 [3,454 kB]
Get:2 http://mirrors.linode.com/debian stretch/main amd64 zsh amd64 5.3.1-4+b2 [816 kB]
Fetched 4,270 kB in 0s (48.7 MB/s)
Selecting previously unselected package zsh-common.
(Reading database ... 34252 files and directories currently installed.)
Preparing to unpack .../zsh-common_5.3.1-4_all.deb ...
Unpacking zsh-common (5.3.1-4) ...
Selecting previously unselected package zsh.
Preparing to unpack .../zsh_5.3.1-4+b2_amd64.deb ...
Unpacking zsh (5.3.1-4+b2) ...
Setting up zsh-common (5.3.1-4) ...
Processing triggers for man-db (2.7.6.1-2) ...
Setting up zsh (5.3.1-4+b2) ...
We can see the zsh version that was installed in the install output, but we can confirm that version is actually running with:
grokman@li598-26:~$ zsh --version
zsh 5.3.1 (x86_64-debian-linux-gnu)
Now, we can set our login shell to be zsh with the chsh command. Note that we have to log out and back in to see the change. When we log back in we get prompted for how we want to configure our zsh. If you have custom config already in mind, press 0. If not you can start with the default option 2:
grokman@li598-26:~$ chsh -s $(which zsh)
Password:
grokman@li598-26:~$ exit
logout
root@li598-26:~# su - grokman
This is the Z Shell configuration function for new users,
zsh-newuser-install.
You are seeing this message because you have no zsh startup files
(the files .zshenv, .zprofile, .zshrc, .zlogin in the directory
~). This function can help you with a few settings that should
make your use of the shell easier.
You can:
(q) Quit and do nothing. The function will be run again next time.
(0) Exit, creating the file ~/.zshrc containing just a comment.
That will prevent this function being run again.
(1) Continue to the main menu.
(2) Populate your ~/.zshrc with the configuration recommended
by the system administrator and exit (you will need to edit
the file by hand, if so desired).
--- Type one of the keys in parentheses --- 2
/home/grokman/.zshrc:15: scalar parameter HISTFILE created globally in function zsh-newuser-install
(eval):1: scalar parameter LS_COLORS created globally in function zsh-newuser-install
grokman@li598-26 ~ %
You will probably notice your prompt change a bit:
⇒ 
To set it up like so: 
We can edit our ~.zshrc file:
grokman@li598-26 ~ % vim .zshrc
Change the contents of the .zshrc to be:
# grokman's basic .zshrc
HISTFILE=~/.histfile
HISTSIZE=1000
SAVEHIST=1000
# The following lines were added by compinstall
zstyle :compinstall filename '/home/grokman/.zshrc'
#
autoload -Uz compinit
compinit
# End of lines added by compinstall
#
#PROMPT
setopt PROMPT_SUBST
PROMPT='%{$(pwd|grep --color=always /)%${#PWD}G%} %(!.%F{red}.%F{cyan})%n%f@%F{yellow}%m%f%(!.%F{red}.)%#%f '
#ALIASES
alias ll='ls -lia'
alias sd='sudo shutdown -r 0'
Save the file & then we can just “source” the .zshrc like so:
grokman@li598-26 ~ % . ~/.zshrcNow your prompt should look like so:
zsh kind of has a bit of a cult following (basically, people who get a bit overly- caught up in the way their prompt looks, haha!). In recent times, a nice little zsh project has cropped up which allows you to kind of go nuts with zsh, giving you the ability to integrate your zsh more tightly with apps like Git, PostgreSQL, Python & many more. Depending on what you’re doing, it may be worthwhile to check it out: Oh My zsh!