Sed

Simple search / replace

sed 's/<search>/<replace>/g'

Remove HTML tags

sed -e 's/<[^>]*>//g' <file>

Remove File Extensions

sed 's/\(.*\)\..*/\1/'

eg:

echo "house.txt" | sed 's/\(.*\)\..*/\1/'  # returns 'house'

Delete Matching Line

sed '/someline/d'

Modifying a File Directly

Using the above tips, you can modify a file directly by using the -i parameter, with the filename as the second argument:

sed -i "search" /path/to/file

Inserting a Line Before/After a Match

Use: 0,/<regex>/s//<replacement text where \0 is the found line>/

# Add a password line before the first title entry in the grub.conf file.
sed -i "0,/^title/s//password --encrypted $Password\n\n\0/" $GrubConfig

To append after, just put \0 before your replacement text.