sed is short for stream editor. It reads in a file (one line at a time), modifies the contents per your parameters, and then outputs. 

Basics

A more simple description, it allows you to modify the contents of a file without you actually having to open it.

Basics

Our sample text file called hey.txt looks like this,

Hey, diddle, diddle,
The cat and the fiddle,
The cow jumped over the moon;
The little dog laughed
To see such sport,
And the dish ran away with the spoon.


Make sure to keep this file in your /opt/nursery/ directory.

Here a simple example of replacing the word original cow with new in a file called notesreindeer in the file hey.txt.,

sed -i 's/originalcow/newreindeer/' notes.txt

The -i signifies inline editing and also will have sed automatically create creates a backup file.

Here is an often used example of escaping a the / (slash) reserved character within the single quote,

sed -i 's/originalopt\/pathnursery/newvar\/pathryhme/' notes.txt # need to escape '/' since we are using it as a separator

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