sed linux command:

sed stands for Stream Editor. As its name advertise it works on stream of text (input file, input pipleline).
General command executation:

sed REGEX INPUTFILE

For instance if you want to replace hi with bye in hibye.txt file:

sed 's/hi/bye/' hibye.txt

It will print the result into standard output (console). If you want to put the output in a file:

sed 's/hi/bye/' hibye.txt > output.txt

Instead of INPUTFILE we can put - which then reads from standard input:

cat hibye.txt | sed 's/hi/bye/' -

Now if you want to put the output in a file:

cat hibye.txt | sed 's/hi/bye/' - > output.txt

As until now you have seen, sed command writes output to standard output, if you want to write the result to the file itself, use -i as below:

sed -i 's/hi/bye' hibye.txt

So in the above command the result will be written to hibye.txt itself.

#linux #sed #regex