sed (Stream Editor) command.
It performs a lot of functions files like searching, finding, replacing, insertion, deletion without opening a file.
Create a file called myfile.txt and add the following data
linux is good OS and Open source
unix is not open source
unix has its education version minix
linux has different distributions
Replace unix with linux in myfile.txt
sed 's/unix/linux/' myfile.txt
In this case, unix word is replaced with linux word but only first occurrence in each line.
Replace unix with linux with nth occurrence of a pattern in a line
sed 's/unix/linux/2' myfile.txt
Replace unix with linux with all the occurrence of a pattern in a line
sed 's/unix/linux/g' myfile.txt
Replace unix with linux from nth occurrence to all the occurrences of a pattern in a line
sed 's/unix/linux/2g' myfile.txt
Replace unix with linux in a specific line
sed '3 s/unix/linux/g' myfile.txt
Deleting lines from a particular file.
sed '3d' myfile.txt
sed '2,4d' myfile.txt
