Overview
ksh provides robust scripting capabilities and an interactive shell environment. It has been widely used, especially in enterprise environments, for its stability and performance, and remains one of the important shells on modern Linux systems.
Key Features
- Full POSIX standard compliance
- Advanced scripting features (arrays, associative arrays, functions, etc.)
- Command-line editing and history (supports vi/emacs modes)
- Performance optimization and stability
- High compatibility with Bourne Shell (sh)
Key Options
The ksh command itself has several options to control its behavior. These options are primarily used when starting the shell or executing scripts.
Execution Modes
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Usage Examples
Examples demonstrating various ways to use ksh.
Starting an Interactive KornShell
kshStarts an interactive shell session by running ksh in the terminal.
Executing a KornShell Script
ksh myscript.kshExecutes a script file written in ksh (e.g., myscript.ksh). If the script file has a shebang line like `#!/bin/ksh` at the beginning, it can be executed directly.
Executing a Single Command
ksh -c "echo 'Hello from KornShell!'"Uses the -c option to execute a specific command with ksh and exit immediately.
Executing a Script from Standard Input
echo 'ls -l' | ksh -sExecutes commands passed via a pipe using ksh.
Installation
ksh is often included by default in many Linux distributions or can be easily installed. Here's how to install it on major distributions.
Debian/Ubuntu
sudo apt update
sudo apt install kshInstalls ksh using the apt package manager.
CentOS/RHEL/Fedora
sudo yum install ksh
# or
sudo dnf install kshInstalls ksh using the yum or dnf package manager.
Tips & Notes
Tips and points to note for more efficient use of ksh.
Script Shebang
You can add `#!/bin/ksh` or `#!/usr/bin/ksh` at the beginning of a ksh script file to specify that the script should be executed with ksh.
- Add `#!/bin/ksh` or `#!/usr/bin/ksh` at the start of the script.
- Grant execute permissions to the script: `chmod +x your_script.ksh`
Command-line Editing Modes
ksh supports vi or emacs style command-line editing modes. You can switch between them using the `set -o` command.
- Enable vi mode: `set -o vi`
- Enable emacs mode: `set -o emacs`
Changing Default Shell
chsh -s /bin/kshYou can change the default login shell for the current user to ksh using the `chsh` command. You will need to log out and log back in for the changes to take effect.
POSIX Compatibility
ksh strictly adheres to the POSIX standard. Therefore, scripts written in ksh are likely to run well on other POSIX-compliant shells (e.g., bash in POSIX mode).