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string sed

[sed] Run and understand Replace nth arbitrary string in each line

created-2025/12/25 updated-2026/03/24

Introduction

This repository runs a sed command to replace any string at a specified number on each line.

Commands that need to be installed

  1. None in paticular

Quickstart

Run the sed command and check that the specified string has been replaced.

ubuntu

echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Output results 
hello sEd command world

Apple
bAnana
cherry

macos

MacPorts

echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Output results 
hello sEd command world

Apple
bAnana
cherry

windows

WSL2

echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Output results 
hello sEd command world

Apple
bAnana
cherry

MSYS2 MINGW64

echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Output results 
hello sEd command world

Apple
bAnana
cherry

Procedure

ubuntu

Click to open details

Advance confirmation

Enter the following command into the terminal and if command not found does not appear, it is OK.

Nothing in paticular

preinstall

Please install the command that shows “command not found” in the terminal using the following command.

Nothing in paticular

command

Executing the following command in the terminal should output a string similar to the following:

echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Detail 
hello sEd command world

Apple
bAnana
cherry

macos

Click to open details

Advance confirmation

Enter the following command into the terminal and if command not found does not appear, it is OK.

Nothing in paticular

*MacOS uses the MacPorts package manager to manage commands. If you haven’t installed it yet, please refer to the MacPorts installation instructions at the link below. Also, set an alias for the command so that you can call the command without conflicting with the existing environment. If you are using this blog for the first time, please refer to the following two articles to set up your environment.

[macos] Steps to install MacPorts
[macos] Setting aliases for commands installed with MacPorts

preinstall

If the command not found appears in the terminal, install it using the following command and set an alias.

Nothing in paticular

command

Executing the following command in the terminal should output a string similar to the following:

echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Detail 
hello sEd command world

Apple
bAnana
cherry

windows

Click to open details

Advance confirmation

Enter the following command into the prompt and if command not found does not appear, it’s OK.

WSL2
Nothing in paticular
MSYS2 MINGW64
Nothing in paticular

*Windows has been confirmed to work with WSL2 and MSYS2 MINGW64. Please install WSL2 if possible, and if you are unable to set it up, you can run it by installing MSYS2, but there may be some commands that can only be run in WSL2. Please refer to the following article for instructions on how to install WSL2 and MSYS2.

[windows] Steps to install WSL2 (Windows Subsystem for Linux)
[Windows] Steps to install msys2

preinstall

If the command not found appears in the prompt, please install it using the following command.

WSL2
Nothing in paticular
MSYS2 MINGW64
Nothing in paticular

command

By executing the following command at the prompt, you should get the following output:

WSL2
echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Detail 
hello sEd command world

Apple
bAnana
cherry
MSYS2 MINGW64
echo "hello sed command world" | sed 's/e/E/2'

 

cat << EOF | sed 's/a/A/1'


apple


banana


cherry


EOF
Detail 
hello sEd command world

Apple
bAnana
cherry

Afterword

It replaces the nth string in each line, so the following code only replaces the line with banana

cat << EOF | sed 's/a/A/2'


apple


banana


cherry


EOF

List of how to use the sed command

There are other articles about the sed command besides this one.
Please check them out at the link below if you’re interested.

List of sed command usage instructions

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