Korn Shell (ksh)

History

The Korn Shell (ksh) was developed by David Korn at AT&T Bell Laboratories in the early 1980s. It was designed to be a comprehensive, high-performance shell that combined the best features of the Bourne Shell (sh) and the C Shell (csh). Korn Shell is known for its scripting capabilities, performance, and compatibility with both Bourne and C Shell scripts.

Features

• Scripting: Supports advanced scripting capabilities.

• Command History: Allows users to recall and edit previous commands.

• Job Control: Manages multiple processes within a single shell session.

• Aliases: Creates shortcuts for frequently used commands.

• Arithmetic Operations: Supports built-in arithmetic operations.

• Arrays: Provides support for one-dimensional arrays.

Basic Commands

Scripting

#!/bin/ksh
# This is a comment
echo "Hello, World!"

#!/bin/ksh
name="John"
echo "Hello, $name!"

#!/bin/ksh
number=10
if [[ $number -gt 5 ]]; then
  echo "The number is greater than 5"
else
  echo "The number is 5 or less"
fi

#!/bin/ksh
for i in {1..5}; do
  echo "Iteration $i"
done

#!/bin/ksh
counter=1
while [[ $counter -le 5 ]]; do
  echo "Counter: $counter"
  ((counter++))
done

#!/bin/ksh
greet() {
  echo "Hello, $1!"
}

greet "Alice"
greet "Bob"

#!/bin/ksh
echo "This is a new file" > newfile.txt

#!/bin/ksh
while IFS= read -r line; do
  echo "$line"
done < newfile.txt

#!/bin/ksh
rm newfile.txt

#!/bin/ksh
source_dir="/path/to/source"
backup_dir="/path/to/backup"
timestamp=$(date +%Y%m%d%H%M%S)
backup_file="$backup_dir/backup_$timestamp.tar.gz"

tar -czf $backup_file $source_dir
echo "Backup created at $backup_file"