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. Changes the 1st pattern to the second pattern.
Example: sed 's/red/blue/' < file.txt Changes "red" to "blue" in file.txt
    cat file.txt | sed 's/one/two/' Changes "one" to "two" in file.txt

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

1. sed man page
2. Grymoire sed tutorial