This is not origionally written by me, my ideas and examples come from useful one line script for sed, which I used as reference for many years. Perhaps just a bit content reorganize.

NUMBERING:

number each line of a file

  Using a tab instead of space will preserve margins.

 sed = filename | sed 'N;s/\n/\t/'

number each line of a file

(number on left, right-aligned)

 sed = filename | sed 'N; s/^/     /; s/ *\(.\{6,\}\)\n/\1  /'

number each line of file, but only print numbers if line is not blank

 sed '/./=' filename | sed '/./N; s/\n/ /'

 count lines

(emulates "wc -l")

 sed -n '$='

 

FILE SPACING:

double space a file

 sed G

What if a file already has blank lines in it? Output file should contain no more than one blank line between lines of text.

 sed '/^$/d;G'

undo double-spacing (assumes even-numbered lines are always blank)

 sed 'n;d'

triple space a file

 sed 'G;G'

Insert a blank line when "regex" matches

 insert a blank line above every line which matches "regex"

 sed '/regex/{x;p;x;}'

 insert a blank line below every line which matches "regex"

 sed '/regex/G'

 insert a blank line above and below every line which matches "regex"

 sed '/regex/{x;p;x;G;}'

 

Manipulate TEXT Whitespace

delete leading whitespace (spaces, tabs) from front of each line

# aligns all text flush left

 sed 's/^[ \t]*//'

delete trailing whitespace (spaces, tabs) from end of each line

 sed 's/[ \t]*$//' 

delete BOTH leading and trailing whitespace from each line

 sed 's/^[ \t]*//;s/[ \t]*$//'

insert 5 blank spaces at beginning of each line (make page offset)

 sed 's/^/     /'

align all text flush right on a 79-column width

 sed -e :a -e 's/^.\{1,78\}$/ &/;ta'  # set at 78 plus 1 space

center all text in the middle of 79-column width.

method 1, spaces at the beginning of the line are significant, and trailing spaces are appended at the end of the line

 sed  -e :a -e 's/^.\{1,77\}$/ & /;ta'

method 2, spaces at the beginning of the line are discarded in centering the line, and no trailing spaces appear at the end of lines.

 sed  -e :a -e 's/^.\{1,77\}$/ &/;ta' -e 's/\( *\)\1/\1/'

 

TEXT SUBSTITUTION:

substitute (find and replace) "foo" with "bar" on each line

 sed 's/foo/bar/'             # replaces only 1st instance in a line
 sed 's/foo/bar/4'            # replaces only 4th instance in a line
 sed 's/foo/bar/g'            # replaces ALL instances in a line
 sed 's/\(.*\)foo\(.*foo\)/\1bar\2/' # replace the next-to-last case
 sed 's/\(.*\)foo/\1bar/'            # replace only the last case

substitute "foo" with "bar" ONLY for lines which contain "baz"

 sed '/baz/s/foo/bar/g'

substitute "foo" with "bar" EXCEPT for lines which contain "baz"

 sed '/baz/!s/foo/bar/g'

change "scarlet" or "ruby" or "puce" to "red"

 sed 's/scarlet/red/g;s/ruby/red/g;s/puce/red/g'   # most seds
 gsed 's/scarlet\|ruby\|puce/red/g'                # GNU sed only

reverse order of lines (emulates "tac")

bug/feature in HHsed v1.5 causes blank lines to be deleted

 sed '1!G;h;$!d' 
 sed -n '1!G;h;$p' 

reverse each character on the line (emulates "rev")

 sed '/\n/!G;s/\(.\)\(.*\n\)/&\2\1/;//D;s/.//'

join pairs of lines side-by-side (like "paste")

 sed '$!N;s/\n/ /'

if a line ends with a backslash, append the next line to it

 sed -e :a -e '/\\$/N; s/\\\n//; ta'

if a line begins with an equal sign, append it to the previous line and replace the "=" with a single space

 sed -e :a -e '$!N;s/\n=/ /;ta' -e 'P;D'

add commas to numeric strings, changing "1234567" to "1,234,567"

 gsed ':a;s/\B[0-9]\{3\}\>/,&/;ta'                     # GNU sed
 sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta'  # other seds

add commas to numbers with decimal points and minus signs (GNU sed)

 gsed -r ':a;s/(^|[^0-9.])([0-9]+)([0-9]{3})/\1\2,\3/g;ta'

add a blank line every 5 lines (after lines 5, 10, 15, 20, etc.)

 gsed '0~5G'                  # GNU sed only
 sed 'n;n;n;n;G;'             # other seds

 

SELECTIVE PRINTING OF CERTAIN LINES:

print first 10 lines of file (emulates behavior of "head")

 sed 10q

print first line of file (emulates "head -1")

 sed q

print the last 10 lines of a file (emulates "tail")

 sed -e :a -e '$q;N;11,$D;ba'

print the last 2 lines of a file (emulates "tail -2")

 sed '$!N;$!D'

print the last line of a file (emulates "tail -1")

 sed '$!d'                    # method 1
 sed -n '$p'                  # method 2

print the next-to-the-last line of a file

 sed -e '$!{h;d;}' -e x              # for 1-line files, print blank line
 sed -e '1{$q;}' -e '$!{h;d;}' -e x  # for 1-line files, print the line
 sed -e '1{$d;}' -e '$!{h;d;}' -e x  # for 1-line files, print nothing

print only lines which match regular expression (emulates "grep")

 sed -n '/regexp/p'           # method 1
 sed '/regexp/!d'             # method 2

print only lines which do NOT match regexp (emulates "grep -v")

 sed -n '/regexp/!p'          # method 1, corresponds to above
 sed '/regexp/d'              # method 2, simpler syntax

print the line immediately before a regexp, but not the line containing the regexp

 sed -n '/regexp/{g;1!p;};h'

print the line immediately after a regexp, but not the line containing the regexp

 sed -n '/regexp/{n;p;}'

print 1 line of context before and after regexp

with line number indicating where the regexp occurred (similar to "grep -A1 -B1")

 sed -n -e '/regexp/{=;x;1!p;g;$!N;p;D;}' -e h

grep for AAA and BBB and CCC (in any order)

 sed '/AAA/!d; /BBB/!d; /CCC/!d'

grep for AAA and BBB and CCC (in that order)

 sed '/AAA.*BBB.*CCC/!d'

grep for AAA or BBB or CCC (emulates "egrep")

 sed -e '/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d    # most seds
 gsed '/AAA\|BBB\|CCC/!d'                        # GNU sed only

print paragraph if it contains AAA (blank lines separate paragraphs)

 # HHsed v1.5 must insert a 'G;' after 'x;' in the next 3 scripts below

 sed -e '/./{H;$!d;}' -e 'x;/AAA/!d;'

print paragraph if it contains AAA and BBB and CCC (in any order)

 sed -e '/./{H;$!d;}' -e 'x;/AAA/!d;/BBB/!d;/CCC/!d'

print paragraph if it contains AAA or BBB or CCC

 sed -e '/./{H;$!d;}' -e 'x;/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d
 gsed '/./{H;$!d;};x;/AAA\|BBB\|CCC/b;d'         # GNU sed only

print only lines of 65 characters or longer

 sed -n '/^.\{65\}/p'

print only lines of less than 65 characters

 sed -n '/^.\{65\}/!p'        # method 1, corresponds to above
 sed '/^.\{65\}/d'            # method 2, simpler synta

print section of file from regular expression to end of file

 sed -n '/regexp/,$p'

print section of file based on line numbers (lines 8-12, inclusive)

 sed -n '8,12p'               # method 1
 sed '8,12!d'                 # method 2

print line number 52

 sed -n '52p'                 # method 1
 sed '52!d'                   # method 2
 sed '52q;d'                  # method 3, efficient on large files

beginning at line 3, print every 7th line

 gsed -n '3~7p'               # GNU sed only
 sed -n '3,${p;n;n;n;n;n;n;}' # other seds

print section of file between two regular expressions (inclusive)

 sed -n '/Iowa/,/Montana/p'             # case sensitive

 

SELECTIVE DELETION OF CERTAIN LINES:


print all of file EXCEPT section between 2 regular expressions

 sed '/Iowa/,/Montana/d'

delete duplicate, consecutive lines from a file (emulates "uniq").

 # First line in a set of duplicate lines is kept, rest are deleted.

 sed '$!N; /^\(.*\)\n\1$/!P; D'

delete duplicate, nonconsecutive lines from a file.

Beware not to overflow the buffer size of the hold space, or else use GNU sed.

 sed -n 'G; s/\n/&&/; /^\([ -~]*\n\).*\n\1/d; s/\n//; h; P'

delete all lines except duplicate lines (emulates "uniq -d").

 sed '$!N; s/^\(.*\)\n\1$/\1/; t; D'

delete the first 10 lines of a file

 sed '1,10d'

delete the last line of a file

 sed '$d'

delete the last 10 lines of a file

 sed -e :a -e '$d;N;2,10ba' -e 'P;D'   # method 1
 sed -n -e :a -e '1,10!{P;N;D;};N;ba'  # method 2

delete every 8th line

 gsed '0~8d'                           # GNU sed only
 sed 'n;n;n;n;n;n;n;d;'                # other seds

delete lines matching pattern

 sed '/pattern/d'

delete ALL blank lines from a file (same as "grep '.' ")

 sed '/^$/d'                           # method 1
 sed '/./!d'                           # method 2

delete all CONSECUTIVE blank lines from file except the first; also
deletes all blank lines from top and end of file (emulates "cat -s")

 sed '/./,/^$/!d'          # method 1, allows 0 blanks at top, 1 at EOF
 sed '/^$/N;/\n$/D'        # method 2, allows 1 blank at top, 0 at EOF

delete all CONSECUTIVE blank lines from file except the first 2:

 sed '/^$/N;/\n$/N;//D'

delete all leading blank lines at top of file

 sed '/./,$!d'

delete all trailing blank lines at end of file

 sed -e :a -e '/^\n*$/{$d;N;ba' -e '}'  # works on all seds
 sed -e :a -e '/^\n*$/N;/\n$/ba'        # ditto, except for gsed 3.02.*

delete the last line of each paragraph

 sed -n '/^$/{p;h;};/./{x;/./p;}'

SPECIAL APPLICATIONS:

 # remove nroff overstrikes (char, backspace) from man pages.

The 'echo' command may need an -e switch if you use Unix System V or bash shell.

 sed "s/.`echo \\\b`//g"    # double quotes required for Unix environment
 sed 's/.^H//g'             # in bash/tcsh, press Ctrl-V and then Ctrl-H
 sed 's/.\x08//g'           # hex expression for sed 1.5, GNU sed, ssed

get Usenet/e-mail message header

 sed '/^$/q'                # deletes everything after first blank line

get Usenet/e-mail message body

 sed '1,/^$/d'              # deletes everything up to first blank line

get Subject header, but remove initial "Subject: " portion

 sed '/^Subject: */!d; s///;q'

get return address header

 sed '/^Reply-To:/q; /^From:/h; /./d;g;q'

 # parse out the address proper. Pulls out the e-mail address by itself
 # from the 1-line return address header (see preceding script)

 sed 's/ *(.*)//; s/>.*//; s/.*[:<] *//'

add a leading angle bracket and space to each line (quote a message)

 sed 's/^/> /'

delete leading angle bracket & space from each line (unquote a message)

 sed 's/^> //'

remove most HTML tags (accommodates multiple-line tags)

 sed -e :a -e 's/<[^>]*>//g;/</N;//ba'

extract multi-part uuencoded binaries, removing extraneous header info

so that only the uuencoded portion remains. Files passed to sed must be passed in the proper order. Version 1 can be entered from the command line

 sed '/^end/,/^begin/d' file1 file2 ... fileX | uudecode   # vers. 1

version 2 can be made into an executable

 sed '/^end/,/^begin/d' "[email protected]" | uudecode                    # vers. 2

sort paragraphs of file alphabetically. Paragraphs are separated by blank lines.

GNU sed uses \v for vertical tab, or any unique char will do.

 sed '/./{H;d;};x;s/\n/={NL}=/g' file | sort | sed '1s/={NL}=//;s/={NL}=/\n/g'
 gsed '/./{H;d};x;y/\n/\v/' file | sort | sed '1s/\v//;y/\v/\n/'


TYPICAL USE:

Sed takes one or more editing commands and applies all of them, in sequence, to each line of input. After all the commands have been applied to the first input line, that line is output and a second input line is taken for processing, and the cycle repeats. The preceding examples assume that input comes from the standard input
device (i.e, the console, normally this will be piped input). One or more filenames can be appended to the command line if the input does not come from stdin. Output is sent to stdout (the screen). Thus:

 cat filename | sed '10q'        # uses piped input
 sed '10q' filename              # same effect, avoids a useless "cat"
 sed '10q' filename > newfile    # redirects output to disk


OPTIMIZING FOR SPEED:

If execution speed needs to be increased (due to large input files or slow processors or hard disks), substitution will be executed more quickly if the "find" expression is specified before giving the "s/.../.../" instruction. Thus:

   sed 's/foo/bar/g' filename         # standard replace command
   sed '/foo/ s/foo/bar/g' filename   # executes more quickly
   sed '/foo/ s//bar/g' filename      # shorthand sed syntax


On line selection or deletion in which you only need to output lines from the first part of the file, a "quit" command (q) in the script will drastically reduce processing time for large files. Thus:

   sed -n '45,50p' filename           # print line nos. 45-50 of a file
   sed -n '51q;45,50p' filename       # same, but executes much faster

 

Comments powered by CComment