CentOS / RHEL: Install KornShell (KSH)

Steps to install ksh in Linux

1. Open the Terminal app.
2. Type the ‘yum install ksh‘ command on CentOS/RHEL.
3. Type the ‘dnf install ksh‘ command on Fedora Linux.
4. Update your shell in /etc/passwd
5. Start using your ksh shell.

Let us see steps in detailed to install KornShell (KSH) on a RHEL/CentOS Linux based system.

How to install the Korn Shell (KSH)

Open a terminal and then type the following yum command to install the ksh shell:
$ sudo yum install ksh
OR
# yum install ksh
Sample outputs:

Loaded plugins: auto-update-debuginfo, protectbase, rhnplugin, security
This system is receiving updates from RHN Classic or RHN Satellite.
0 packages excluded due to repository protections
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package ksh.x86_64 0:20100621-19.el6_4.4 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package  Arch        Version                   Repository                 Size
================================================================================
Installing:
 ksh      x86_64      20100621-19.el6_4.4       rhel-x86_64-server-6      687 k
 
Transaction Summary
================================================================================
Install       1 Package(s)
 
Total download size: 687 k
Installed size: 0  
Is this ok [y/N]: y
Downloading Packages:
ksh-20100621-19.el6_4.4.x86_64.rpm                       | 687 kB     00:00     
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : ksh-20100621-19.el6_4.4.x86_64                               1/1 
  Verifying  : ksh-20100621-19.el6_4.4.x86_64                               1/1 
 
Installed:
  ksh.x86_64 0:20100621-19.el6_4.4                                              
 
Complete!

A note about Fedora Linux users

Type the following command to install ksh on Fedora Linux:
$ sudo dnf install ksh

How can I find out path for ksh shell?

To find out path to the ksh, type:
$ whereis ksh
OR use the grep command as follows:
$ grep --color ksh /etc/shells
Sample outputs:

Fig.01: Finding ksh path

/bin/bash
/bin/csh
/bin/ksh
/bin/sh
/bin/tcsh
/bin/zsh

How do I set ksh as a default shell?

The superuser (root) may change the login shell for any account using any one of the following syntax:
$ sudo chsh -s /bin/ksh UserNameHere
OR
# chsh -s /bin/ksh UserNameHere
In this example, set default login shell to /bin/ksh for nixcraft user:
# chsh -s /bin/ksh nixcraft
Regular user can type the following command to change their shell to the ksh:
$ chsh -s /bin/ksh
Logout and login again. Verify your shell with the following command:
$ echo $SHELL
Sample outputs:

/bin/ksh

To see ksh version, type:
$ ksh --version
Sample outputs:

  version         sh (AT&T Research) 93t+ 2010-06-21

Sample ksh program

Create a file called test.ksh using a text editor:

#!/bin/ksh
# Name: test.ksh
# Purpose: My first ksh script
# Author: nixCraft <www.cyberciti.biz> under GPL v2.x+
# ------------------------------------------------------------------------
# set variables 
FILE="/etc/passwd"
NOW="$(date)"
HOSTNAME="`hostname`"
USERS_ACCOUNT="$(wc -l $FILE)"
 
# Greet user
print "Hi, $USER. I'm $0. I'm $SHELL script running on $HOSTNAME at $NOW." 
print 
print "*** User accounts: $USERS_ACCOUNT"
print "*** Current working directory: $PWD"
 
print "*** Running for loop test just for fun:"
for x in {1..3}
do
    print "Welcome $x times."
done

Save and close the file. Run it as follows:

chmod +x test.sh
./test.sh

Sample outputs:

Fig.02 Ksh script in action.

See also:

• Debian / Ubuntu Linux: Install KSH
• See man pages for more info whereis(1)