reverse a string on Linux and Windows

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How to reverse a string on Linux and Windows

On Linux:

  1. Using the rev command: The rev command is a utility that reverses the lines of a file or the characters in a string. To reverse a string, you can use the echo command to pass the string to rev:
echo "string" | rev
  1. Using the sed command: The sed command is a powerful utility that can perform various text transformations. To reverse a string, you can use the sed command with the -r option and the 's/.*(.)/\1/g' expression:
echo "string" | sed -r 's/.*(.)/\1/g'
  1. Using the awk command: The awk command is a programming language that is used for text processing. To reverse a string, you can use the awk command with the {print} action:
echo "string" | awk '{print $1}'

On Windows:

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  1. Using the powershell command: The powershell command is a shell that provides a command-line interface for Windows. To reverse a string, you can use the powershell command with the -C option and the '[System.Text.Encoding]::Unicode.GetString([System.Text.Encoding]::Unicode.GetBytes("string"))' expression:
powershell -C "[System.Text.Encoding]::Unicode.GetString([System.Text.Encoding]::Unicode.GetBytes("string"))"
  1. Using the cmd command: The cmd command is the command-line interpreter for Windows. To reverse a string, you can use the cmd command with the for loop:
cmd /c "for /L %i in (1,1,%len%) do @echo !string:~%len%-%i,1!"

These are some ways to reverse a string on Linux and Windows. There are other ways to achieve this, using different utilities or programming languages.

Via shell script on Linux

reverse a string on Linux and Windows

sh-3.2# vi reverse.sh
#### Start Script #####
#!/bin/bash
input_string=”$1″
reverse_string=””

input_string_length=${#input_string}
for (( i=$input_string_length-1; i>=0; i– ))
do
reverse_string=”$reverse_string${input_string:$i:1}”
done


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echo “$reverse_string”
##### End Script #####

Let’s run it:

sh-3.2# chmod 775 reverse.sh
sh-3.2# ./reverse.sh Etienne
enneitE

Via powershell script on Windows

#Let’s use the script reverse.ps1 below.
######
$string=”Etienne”
$string_array=$string -split “”
[array]::Reverse($string_array)
$string_array -join ”

#####Output#####
PS C:\Users\etienne_noumen\Documents\Etienne\Scripting> .\reverse.ps1

E t i e n n e

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enneitE

Via powershell script on Windows in one line

([regex]::Matches($String,’.’,’RightToLeft’) | ForEach {$_.value}) -join ”

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Via batch script on Windows

::Note: ReverseStr also calls StrLen
::and string length is not greater than 80 chars
:: but can be changed.

@echo off
SetLocal EnableDelayedExpansion
cls
set Str=Etienne
call :StrLen %Str%
echo Length=%Len%
call :ReverseStr %Str%
echo String=%Str%
echo Reverse Str=%Reverse%
exit /b

::—————-
:: Calc Var Length
::—————-
:: %*=Str to Check
:: Returns %Len%
:: —————
:StrLen %*
set Data=%*
for /L %%a in (0,1,80) do (
set Char=!Data:~%%a,1!
if not “!Char!”==”” (
set /a Len=%%a+1
) else (exit /b)
)
exit /b

::—————
:: Reverse String
::—————
:: %* Str to Reverse
:: Returns %Reverse%
::——————
:ReverseStr %*
set Data=%*
call :StrLen %Data%
for /L %%a in (!Len!,-1,0) do (
set Char=!Data:~%%a,1!
set Reverse=!Reverse!!Char!
)
exit /b

Via perl script on Windows or Linux

Via python script on Windows or Linux

def reverse_string(a_string)
return a_string[::-1]
reverse_string(“etienne”) returns “enneite”
Source:

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