Sed
Sed is a stream editor. A stream editor is used to perform basic text transformations on an input stream (a file or input from a pipeline). Sed is similar editors that script edits, but sed only makes one pass over the input(s), and thus is more efficient. But it is sed's ability to filter text in a pipeline which particularly distinguishes it from other types of editors.
Commands
: label
# comment
{....} Block
= print line number
a \ Append
b label Branch
c \ change
d and D Delete
g and G Get
h and H Hold
i \ Insert
l Look
n and N Next
p and P Print
q Quit
r filename Read File
s/..../..../ Substitute
t label Test
w filename Write Filename
x eXchange
y/..../..../ Transform
sed Pattern Flags
/g Global
/I Ignore Case
/p Print
/w filename Write Filename
References