1. sed“d” command lets us print specific lines based on the line number or regex provided.
2. When ^ means beginning of the line and $ denotes end of the line, ^$ makes a “Blank Line”, very useful while removing empty lines from a file.

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1. sed“a” command lets us append lines to a file, based on the line number or regex provided. So, the lines will be added to the file AFTER the line where condition matches.
2.  sed“i” command lets us insert lines in a file, based on the line number or regex provided. So, the lines will be added to the file AT the location where line number matches or BEFORE the line where pattern matches.
3. sed with option -i will edit the file in place, i.e. unless you use the option -i, the changes will not be written to the file.

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Here is the brief introduction of the Super sed:

• sed stand for Stream EDitor and it being based on the ed editor, it borrows most of the commands from the ed. It was developed by Lee E. McMahon of Bell Labs.
• sed offers large range of text transformations that include printing lines, deleting lines, editing line in-place, search and replace, appending and inserting lines, etc.
• sed is useful whenever you need to perform common editing operations on multiple lines without using ‘vi’ editor.
• Whenever sed is executed on an input file or on the contents from stdin, sed reads the file line-by-line and after removing the trailing newline, places it in the “Pattern space”, where the commands are executed on them after conditions (as in case of regex matching) are verified, and then printed on the stdout.

Printing Lines from a File using sed

Before we start, just remember two points:

1. sed“p” command lets us print specific lines based on the line number or regex provided.
2. sed with option -n will suppress automatic printing of pattern buffer/space. So, we would want to use this option. (Explained in later section)

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