Sed Examples for Append, Insert and Replace a line in file

Sed For Append, Insert and Replace a line in a file
Append a Line :-
Syntax :-
sed 'ADDRESS a\
    Line which you want to append' filename

    (OR)

sed '/PATTERN/ a\
    Line which you want to append' filename


Example1 :-Append a line after the 2nd line of the file

sed '2 a\
Add H/W - Mouse, Headphone' config_details.txt


Example2 :-Append a line after the matching word in a line of the file


sed '/Window/ a\
Add H/W - Mouse, Headphone' config_details.txt


Example3 :- Append a line at the end of the file

sed '$ a\
Add H/W - Mouse, Headphone' config_details.txt

Insert a Line :-

Syntax :-sed 'ADDRESS i\
    Line which you want to append' filename

    (OR)

sed '/PATTERN/ i\
    Line which you want to append' filename


Example1 :-Append a line before the 2nd line of the file

sed '2 i\
Add H/W - Mouse, Headphone' config_details.txt


Example2 :-Append a line before the matching word in a line of the file


sed '/Window/ i\
Add H/W - Mouse, Headphone' config_details.txt


Example3 :- Append a line before last line of the file

sed '$ i\
Add H/W - Mouse, Headphone' config_details.txt


Replace a Line :-

Syntax :-
sed 'ADDRESS c\
    Line which you want to append' filename

    (OR)

sed '/PATTERN/ c\
    Line which you want to append' filename


Example1 :-Replace 2nd line of the file

sed '2 c\
Add H/W - Mouse, Headphone' config_details.txt


Example2 :-Replace matching word line of the file


sed '/Window/ c\
Add H/W - Mouse, Headphone' config_details.txt


Example3 :- Replace last line of the file

sed '$ c\
Add H/W - Mouse, Headphone' config_details.txt

Server To Server Password less connectivity setup

Server To Server Password less connectivity setup
Here I have below two server

First Server :-192.168.2.100
Second Server :-192.168.2.101

I need password less connectivity from "First Server" to "Second Server".

Login to First Server (192.168.2.100) and perform below steps

Step 1: Create Authentication SSH-Kegen Keys on First Server

ssh-keygen -t rsa

Step 2: Create .ssh Directory on Second Server from First server

ssh user@192.168.2.101 mkdir -p .ssh

Step 3: Upload Generated Public Keys on Second Server from First Server

cat .ssh/id_rsa.pub | ssh user@192.168.2.101 'cat >> .ssh/authorized_keys'

Step 4: Set Permissions on Key File on Second Server from First Server

ssh user@192.168.2.101 "chmod 700 .ssh; chmod 640 .ssh/authorized_keys"