sed-one-liners

Basic understanding

sed 's/<match-pattern>/<replace-pattern>/g' <some-filename.txt>
to replace infile sed -i 's/<....

Switches

/g (global)
/p (print)
/I (ignore case)
/w some-filename (write to some-filename)

Substitute command 's/...'

/../../ Delimiter
match-pattern Regular Expression Pattern Search Pattern
replacement-pattern Replacement string

Transliterate command 'y/...'

y/source/dest/
Transliterate the characters in the pattern space which appear in source to the corresponding character in dest.
one to one mapping
Example : 'y/0123/_abc/' replaces the stream as
- 0 -> _
- 1 -> a
- 2 -> b
- 3 -> c

Delimiters

/ is not the only delimiter. Use # or _ or anything convinient

Chain and pipe expressions

sed -e 'first-expression' -e 'second-expression' ... cat some-file-input | sed 'some-expression'

REFERENCES

http://www.grymoire.com/Unix/Sed.html#uh-1