Lesson 9

Date: 3/26/2014
Linux shell scripting tutorial
Linux for Engineering and IT Applications


Introduction to SED

String editor, sed, is used for editing lines in a file or a stream; output is going to the standard output and can be re-directed to a new file.
Syntax: 
sed [options] 'command1' [files]
sed [options] -e 'command1' [-e command2 ...] [files]
sed [options] -f script [files]

Delete lines from 3 through 5 in file list.txt: 
sed '3,5d' list.txt

Delete lines that contain "O" at the beginning of the line: 
sed '/^O/d' list.txt

Translate capital C,R,O into small c,r,o: 
sed 'y/CRO/cro/' list.txt

Delete ampty lines: 
sed '/^$/d' list.txt

Replace string Oop with Wee for the first occurence on a line 
sed 's/Oop/Wee/' lsst.txt

Remove ss string (replace with empty entry)for the first occurence on a line: 
sed 's/ss//' list.txt

Remove ss string for all occurences on a line: 
sed 's/ss//g' list.txt

Substitute a single space for any number of spaces wherever they occur on the line: 
sed 's/ */ /g' list.txt

Substitute underscore for any number of spaces wherever they occur on the line: 
sed 's/ */_/g' list.txt


More examples: Useful one-line scripts for sed
Recommended tutorial: The GNU sed stream editor

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