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How to Reverse a String using Unix Shell Programming?
Bash is a shell or command line interpreter. It is a layer programming language that understands and executes the command that a user enters or can read commands from a script. Essentially Bash or Shell allows users of Unix-like systems and Windows via a Windows subsystem for Linux to control the innermost components of the Operating system using text-based commands.
In this article, we will discuss a problem to be solved by Shell scripting. We are given a String, and we need to print the reverse of that string using Shell Programming. For example,
Input : str = “ Hello ” Output : “ olleH ” Explanation : Reverse order of string “ Hello ” is “ olleH ”. Input : str = “ yam ” Output : “ may ”
Approach to find The Solution
- Declare two strings, one to store the given string and the other to store reversed string.
- Find the length of the given string.
- Traverse the string from [length - 1]th index to 1 using a for a loop.
- Append every character to the reversed_string variable.
- Finally, print the reversed_string using echo.
Example
#!/bin/bash # declaring variable to store string # and catching the string passed from shell str="$1" reversed_string="" # finding the length of string len=${#str} # traverse the string in reverse order. for (( i=$len-1; i>=0; i-- )) do reversed_string="$reversed_string${str:$i:1}" done # printing the reversed string. echo "$reversed_string"
Input
Hello
Output
olleH
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