1. Technology
You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

Example uses of sed

An introductory tutorial

By

Man typing on computer
Paul Harizan/Stockbyte/Getty Images
A common use of sed is to modify each line of a file or stream by replacing specified parts of the line. For example if you have a file that contains the lines:

1, Justin Timberlake, Title 545, Price $6.30
2, Taylor Swift, Title 723, Price $7.90
3, Mick Jagger, Title 610, Price $7.90
4, Lady Gaga, Title 118, Price $6.30
5, Johnny Cash, Title 482, Price $6.50
6, Elvis Presley, Title 335, Price $6.30
7, John Lennon, Title 271, Price $7.90
If the file name is "songs.txt" and you wanted to change all occurrences of 6.30 to 7.30 you could use the command:

sed 's/6.30/7.30/' songs.txt > songs2.txt
which writes the modified file to "songs2.txt". So the output file would contain:

1, Justin Timberlake, Title 545, Price $7.30
2, Taylor Swift, Title 723, Price $7.90
3, Mick Jagger, Title 610, Price $7.90
4, Lady Gaga, Title 118, Price $7.30
5, Johnny Cash, Title 482, Price $6.50
6, Elvis Presley, Title 335, Price $7.30
7, John Lennon, Title 271, Price $7.90
If you wanted replace all occurrences of "Cash" with "Trash" you would be use:

sed 's/Cash/Trash/' songs.txt > songs2.txt
which would create a file with content:

1, Justin Timberlake, Title 545, Price $7:30
2, Taylor Swift, Title 723, Price $7.90
3, Mick Jagger, Title 610, Price $7.90
4, Lady Gaga, Title 118, Price $7:30
5, Johnny Trash, Title 482, Price $6.50
6, Elvis Presley, Title 335, Price $7:30
7, John Lennon, Title 271, Price $7.90
Sed is also frequently used to filter lines in a file or stream. For example if you only want see the lines containing "John" you could use:

sed -n '/John/p' songs.txt > johns.txt
which will write the following lines to file johns.txt:

5, Johnny Trash, Title 482, Price $6.50
7, John Lennon, Title 271, Price $7.90
  1. About.com
  2. Technology
  3. Linux
  4. Linux / Shell Commands
  5. Examples of how to use the command sed

©2014 About.com. All rights reserved.