SED-Replace multiple lines with a single line

A useful option of sed command to replace multiple lines with a single line upon matching a given string.

$ cat -n file.txt
Hello world
Hello nobody
nobody
Somebody
anybody

If you want to replace the lines 2 and 3 with another line "Hello everybody" the below command will help.

$ sed '/nobody$/{N;s/Hello nobody\nnobody/Hello everybody/}' file.txt

$ cat -n file.txt
1 hello world
2 Hello everybody
3 Somebody
4 anybody

Comments

Check remote UDP connectivity from Linux

Hi there, You all know how to check TCP port connectivity from a Linux or UNIX machine to a remote machine using telnet as per th example below $ telnet 127.0.0.1 25 but we can't adopt TELNET to check UDP connectivity. Linux and most of the UNIXes come with a network layer utility called nc (abbreviation for netcat) which is very useful to check UDP connectivity and to explore a lot with both TCP and UDP. An example is shown below # nc -v -u -z -w 3 172.24.16.131 123 Connection to 172.24.16.131 123 port [udp/ntp] succeeded!

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PING.sh

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