Differences Between Bash and Korn Shells

1. Overview

The shell plays an important role in the automation of day-to-day activities executed by Linux users. In Linux environments, several shells support the development and execution of effective and efficient automated operations. We’ll talk about two of the most popular ones.

In this tutorial, we’ll outline and discuss the differences between the Bash and Korn shells.

2. Scalability

The scalability of a shell determines its capacity to carry out a wide variety of tasks efficiently.

2.1. Bash

Bash is less scalable and only capable of performing simple command execution and basic scripting and automation. Although it’s the default shell in major Linux distributions, one weakness of Bash is that it’s limited to small and medium-sized tasks and isn’t generally well-suited for handling very large-scale or resource-intensive tasks.

2.2. Korn

The Korn shell offers overall better scalability. It can arguably handle several operations better than Bash:

• data manipulation
• mathematical operations
• advanced scripting

It’s also excellent for Linux users who need to execute complex and advanced tasks.

Overall, it’s easier to handle larger scripts and resource-intensive tasks more effectively with the Korn shell than with the Bash shell.

3. Customization

Customizing a shell involves creating shortcuts and functions that increase shell productivity. It also helps to simplify tasks and personalize the environment to our needs.

3.1. Bash

Bash provides the .bash_profile and the .bashrc configuration files. Through these files, users can personalize the shell settings, configure prompts, create environmental variables, and even customize the shell settings through these configuration files:

$ PS1="CustomBashPrompt> "
CustomBashPrompt>

In this case, we see an example of prompt customization. Here, the PS1 is an environmental variable that defines the primary prompt for Bash. The value of PS1 defines the shell’s prompt.

3.2. Korn

The Korn shell also provides similar customization options:

• prompt customization
• shell behavior

Let’s see how we can customize the prompt of Korn:

$ PS1="CustomKornPrompt"
CustomKornPrompt>

In terms of prompt customization, the Bash and Korn shells are fairly similar in structure.

However, because the Bash shell has become widely used and established, customizations in Bash are more likely to function smoothly and effectively across different systems and distributions. This is one of the advantages the Bash shell has over the Korn shell in terms of customization choices.

4. Open Source Licensing

License terms can have a significant effect on the accessibility and usage of software.

4.1. Bash

Bash is open source and freely available since it’s offered under the GNU General Public License. The fact that Bash is open source has also helped to boost its widespread adoption.

4.2. Korn

Korn shell is available in many versions each with its own set of licensing rules. While the ksh88 version is freely available, the ksh93 is offered under a more restrictive license.

In terms of open-source licensing, the Bash shell is completely open-source and freely available under the GNU General Public License, while the Korn shell’s ksh93 version is offered under a more restrictive license.

5. Syntax

The syntax of a Linux shell is an important factor to consider when choosing between Bash and Korn shells.

5.1. Bash

The syntax of Bash is well-documented. It also provides users with a variety of scripting constructs:

• conditional expressions
• variables
• loops
• functions

Let’s see an example of a conditional if statement:

$ if [[ $var == "value" ]]; then 
  echo "This is a Bash specific conditional expression."
  fi

Here, the Bash shell introduces [[ for extended conditional expressions, which isn’t available in the Korn shell. It checks if the variable $var is equal to 1.

Syntax knowledge is fundamental for effective productivity in shell scripting. Thus, extras on top of the basic POSIX constructs can be a welcome way to simplify functionality. On the other hand, sticking to the standard can be beneficial for portability.

5.2. Korn

The Korn shell also features a fairly easy-to-use syntax. In particular, Korn excels mostly at scripting tasks that demand extensive data manipulation, floating point arithmetic, and arrays of variables:

$ typeset -i number=42

Here, the Korn shell introduces typeset for variable attributes, which differs from Bash’s declare attribute.

Overall, Korn can be better and outperform Bash, but this usually comes at the cost of reduced readability and harder development and maintenance.

6. Performance

Performance is also a critical factor to consider when comparing the capabilities of shells.

6.1. Bash

The Bash shell is well known for its constant and dependable performance. It handles day-to-day operations effectively and it’s also extensively used for scripting:

$ time for i in {1..100000}; do
  echo "baeldung $i"
done
[...]

real    0m0.761s
user    0m0.435s
sys     0m0.324s

Here, we have a simple for loop in Bash that generates baeldung followed by the value of i and loops from 1 to 100000. The time command is also used by the loop to calculate its execution time. Where the real time is the total elapsed time. The user time represents the time the CPU spends in user-mode code. The sys time represents the time the CPU spends in system-mode code. In this case, the Bash shell took approximately 0.761 seconds to complete the task.

This example shows Bash’s basic capability to handle loops, since they are the main drivers and bigger and long-running tasks. While in some ways slower than Korn shell, it however performs adequately in a wide range of situations.

6.2. Korn

When it comes to complex scripting requirements, the Korn shell performs brilliantly unlike the Bash shell. It’s also great in situations that require efficient power:

• data manipulation
• advanced mathematics
• process replacement

Let’s explore an example:

$ time for ((i=1; i<=1000; i++)); do
  print "baeldung $i"
done
[...]

real    0m00.37s
user    0m00.17s
sys     0m00.19s

Here, the output structure is similar to the Bash shell output. In this case, the Korn shell took approximately 00.37 seconds to complete the task which is significantly faster than the Bash shell’s 0.761.

This showcases the Korn shell’s ability to execute script tasks faster, so it’s useful for power users and users who require outstanding system performance.

7. Portability

When deciding between the Bash and Korn shells, we should also take into consideration the portability of shell scripts, especially if we require our scripts to be able to function reliably across different Linux platforms.

7.1. Bash

Because Bash is the default shell on many Linux systems including multiple versions of Linux and the Mac operating system, Bash scripts are very portable. Bash scripts have also grown to be widely used, so they’re more likely to function correctly without changes across multiple platforms.

Overall, this is one of the biggest advantages of Bash.

7.2. Korn

Korn shell scripts often need to be modified when moved between systems for several reasons:

• might not be accessible out of the box on various Linux platforms
• non-portable high-level features
• variety of versions, each with its own licensing rules
• complicated to maintain consistent behavior across different systems

Thus, when using Korn shell scripts on multiple platforms, we should be aware of potential compatibility difficulties. Further, Korn documentation is scarce, so porting is made even more difficult.

8. History Management

History management is important for the convenient retrieval and reuse of earlier executed commands. Both the Bash and Korn shells keep a command history but in slightly different ways.

8.1. Bash

Bash saves command history in a file called .bash_history. Users may just go through and browse through their command-line history by using the up and down arrow keys or Ctrl+R. Bash also offers some options for changing how it handles its history function:

$ history

This Bash code demonstrates how to view the command history using the history command. It lists previously executed commands, making it easy for users to recall and reuse them.

8.2. Korn

The Korn shell has a different and less straightforward process when it comes to history management. Although users can view and edit their history with shortcuts, the command-line settings available are different from those available in Bash:

$ fc -l

In this Korn shell example, we use the fc -l command to list the command history.

However, if we ever consider switching to Korn from Bash, we may need to familiarize ourselves with the history management commands and style of the Korn shell.

9. Task Management

Task management is also a fundamental feature of Linux shells, enabling users to effectively monitor and control operations, particularly when working on challenging processes. Both the Bash and Korn shells offer efficient task management.

9.1. Bash

Bash has become well known for its powerful and user-friendly task management tools, including jobs and job identifiers which make task management commands more precise.

In particular, it’s usually easy to use the foreground fg and the background bg commands. These commands are used for handling background and foreground tasks enabling users to quickly switch between the foreground and background processes:

$ sleep 10 &
[1] 28362
$ jobs
[1]+ Running sleep 10 &
$ fg %1
sleep 10
[Ctrl + z]
[1]+  Stopped sleep 10
$ bg %1
[1]+  Running sleep 10 &

The jobs command lists the background tasks, displaying [1]+ Running sleep 10 & to indicate that the task is running in the background. When we use fg %1, it brings the first available background task to the foreground. Pressing Ctrl+Z suspends the task. Finally, we resume the suspended task in the background with bg %1, which shows that the background task is up and running.

9.2. Korn

The Korn shell provides similar features and functionality for job management:

$ sleep 10 &
[1] 81602
$ jobs
[1]+ Running sleep 10 &
$ fg
sleep 10
[Ctrl + z]
[1] = Stopped sleep 10
$ bg
[1]+ Running sleep 10 &

Explicit job identifiers like %1 used to refer to the first job enable users to easily understand the scope of the task management command. Both shells support this along with most job control features.

10. Conclusion

In this article, we discussed the key differences between Bash and Korn shells.

In summary, Bash is widely used and also an excellent choice for cross-platform general-purpose work as well as scripting tasks. On the other hand, the Korn shell excels in advanced scripting and faster performance but lacks in documentation and portability.

Additionally, the choice between Bash and Korn shell is determined by the nature of the task at hand. Bash is a reliable solution for everyday operations and basic scripting. The Korn shell, on the other hand, provides more scalability and efficiency for intense, performance-critical tasks.

We’ve also seen some crucial considerations for Linux shell administration. These considerations help us make informed choices when selecting a Linux shell.