SED delete, print and grouping

SED delete

A useful command that deletes line that matches the restriction: "d." For example, if you want to chop off the header of a mail message, which is everything up to the first blank line, use:

$ sed '1,/^$/d' file

SED print

If sed was not started with an "-n" option, the "p" command will duplicate the input.

sed '/^$/ p' file

Adding the “-n” option turns off printing unless you request it.

SED grouping

The curly braces, "{" and "}" are used to group the commands.

Previously, we have showed you how to remove comments starting with a "#." If you wanted to restrict the removal to lines between special "begin" and "end" key words, we use:

sed -n '
	/begin/,/end/ {
	     s/#.*//
	     s/[ ^I]*$//
	     /^$/ d
	     p
	}
' file