Sed

-i – Modify and save the specified document.

Replace foo with too in the first line found.
$ sed -i ‘s/foo/too/’

Replace foo with too throughout the entire file.
$ sed -i ‘s/foo/too/g’

Delete the 14th line.
$ sed -i ‘14d’ /file

Delete the line containing Network or network.
$ sed -i ‘/[Nn]etwork/d’ /file

Add “[mounts]” to the end of the file, then a new line and “user root”.
$ sed -i ‘$ a \\n[mounts]\nuser root’ /etc/munin/config

After the 14th line, add “echo ”graph_category logger“”.
$ sed ‘14a\ echo \“graph_category logger\”’ /etc/munin/plugins/command

Insert ‘# vim: ft=ruby’ and a line break at the beginning of the file.
$ sed ‘1i # vim: ft=ruby\n’

Replace repeated empty lines with a single empty line.
$ sed -e ‘:a;/^$/N;/\n$/{D;ba}’ file.txt

Convert DOS line breaks (CR/LF) to Unix (LF)
$ sed ‘s/.$//’ dosfile.txt > unixfile.txt

Replace string1 with string2
$ sed ‘s/string1/string2/g’

Change string anystring1 to anystring2
$ sed ‘s/\(.*\)1/\12/g’

Remove comments and empty lines
$ sed ‘/ *#/d; /^ *$/d’
sed -i “/^$/d” file.txt #-i for changes within the document

Join strings (lines) with preceding \
$ sed ‘:a; /\\$/N; s/\\\n//; ta’

Remove preceding spaces from strings
$ sed ‘s/[ \t]*$//’

Escape active shell metacharacters with double quotes
$ sed ‘s/\([\\`\\”$\\\\]\)/\\\1/g’

Align numbers to the right margin
$ seq 10 | sed “s/^/ /; s/ *\(.\{7,\}\)/\1/”

Print the 1000th line
$ sed -n ‘1000p;1000q’

Print lines 10 through 20
$ sed -n ‘10,20p;20q’

Get the title from an HTML page
$ sed -n ‘s/.*

 

Partially taken from here, thanks to the author!