sed | Alex's Second Brain

sed

Stream editor for filtering and transforming text

[me@linuxbox ~]$ echo "front" | sed 's/front/back/'
back

sed will accept any character that follows the character as the delimiter.

[me@linuxbox ~]$ echo "front" | sed 's_front_back_'
back~

Most commands in sed can be preceded by an address, specifying which lines of input streams are to be edited.

[me@linuxbox ~]$ echo "front" | sed '1s/front/back/'
back

Address	Description
n	A line number where n is a positive integer
$	The last line.
regexp	Lines matching a POSIX basic regular expresion.
	Note that the regex is delimited by slash characters.
	Optionally, the regex may be delimited by an alternate char,
	by specifying the expression with , where c is alternate.
addr1,addr2	A range of lines from addr1 to addr2, inclusive
first~step	Match the line represented by the number first, then each
	subsequent line at step intervals.
addr1,+n	Match addr1 and the following n lines.
addr!	Match all lines except addr, which may be any of the forms listed earlier

sed Address Notation

Command	Description
=	Output the current line number
a	Append text after the current line
d	Delete the current line
i	Insert text in front of the current line
p	Print the current line. By default, sed prints every line and
	only edits lines that match specified address within the file
q	Exit sed without processing any more lines. If the -n option
	is not specified, output the current line.
Q	Exit sed without processing any more lines
s/regex/replacement/	Substitute the contents of replacement wherever regex
y/set1/set2	Transliterate by converting chars from set1 to chars in set2

sed Basic Editing Commands