SED
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General Use
SED can be used to:
- replace a sting with a new string
- remove unwanted characters
Handy One Liners
;HANDY ONE-LINERS FOR SED (Unix stream editor) Oct. 29, 1997
:compiled by Eric Pement <epement@jpusa.chi.il.us> version 4.3
:Latest version of this file is always at <http://www.wollery.demon.co.uk>
==FILE SPACING:==
===double space a file===
sed G
===triple space a file===
sed 'G;G'
===undo double-spacing (assumes even-numbered lines are always blank)===
sed 'n;d'
==NUMBERING:==
===number each line of a file (simple left alignment). Using a tab (see note on '\t' at end of file) 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 '$='
==TEXT CONVERSION AND SUBSTITUTION:==
===IN UNIX ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format ===
sed 's/.$//'
===IN DOS ENVIRONMENT: convert Unix newlines (LF) to DOS format ===
sed 's/$//' # method 1
sed -n p # method 2
===delete leading whitespace (spaces, tabs) from front of each line aligns all text flush left ===
sed 's/^[ \t]*//' # see note on '\t' at end of file
===delete trailing whitespace (spaces, tabs) from end of each line===
sed 's/[ \t]*$//' # see note on '\t' at end of file
===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. In method 1, spaces at the beginning of the line are significant, and trailing spaces are appended at the end of the line. In 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\}$/ & /;ta' # method 1
sed -e :a -e 's/^.\{1,77\}$/ &/;ta' -e 's/\( *\)\1/\1/' # method 2
===substitute (find & 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
===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'
===reverse order of lines (emulates "tac") ===
sed '1!G;h;$!d'
===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/ /'
==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 last 10 lines of file (emulates "tail") ===
sed -e :a -e '$q;N;11,$D;ba'
===print last line of file (emulates "tail -1") ===
sed '$!d'
===print only lines which match regular expression (emulates "grep") ===
sed -n '/regexp/p' # method 1
sed '/regexp/!d' # method 2
===print only lines which do NOT match regexp (emulates "grep -v") ===
sed -n '/regexp/!p' # method 1, corresponds to above
sed '/regexp/d' # method 2, simpler syntax
===print 1 line of context before and after regexp, with line number indicating where the regexp occurred (similar to "grep -A1 -B1") ===
sed -n -e '/regexp/{=;x;1!p;g;$!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 or BBB or CCC (emulates "egrep") ===
sed -e '/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d
===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 syntax
===print section of file from regular expression to end of file ===
sed -n '/regexp/,$p'
===print section of file based on line numbers (lines 8-12, inclusive) ===
sed -n '8,12p' # method 1
sed '8,12!d' # method 2
===print line number 52 ===
sed -n '52p' # method 1
sed '52!d' # method 2
sed '52q;d' # method 3, efficient on large files
===print section of file between two regular expressions (inclusive) ===
sed -n '/Iowa/,/Montana/p' # case sensitive
==SELECTIVE DELETION OF CERTAIN LINES:==
===print all of file EXCEPT section between 2 regular expressions ===
sed '/Iowa/,/Montana/d'
===delete duplicate lines from a sorted file (emulates "uniq"). First line in a set of duplicate lines is kept, the rest are deleted ===
sed '$!N; /^\(.*\)\n\1$/!P; D'
===delete ALL blank lines from a file (same as "grep '.' ") ===
sed '/^$/d'
===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*$/N;/\n$/ba'
==SPECIAL APPLICATIONS:==
===remove nroff overstrikes (char, backspace) from man pages===
sed "s/.`echo \\\b`//g" # double quotes required for Unix environment
sed 's/.\x08//g' # hex expression for GNU sed (octal is "\010")
===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;s/\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; version 2 can be made into an executable Unix shell script. (Modified from a script by Rahul Dhesi.) ===
sed '/^end/,/^begin/d' file1 file2 ... fileX | uudecode # vers. 1
sed '/^end/,/^begin/d' $* | uudecode # vers. 2
===zip up each .TXT file individually, deleting the source file and setting the name of each .ZIP file to the basename of the .TXT file (under DOS: the "dir /b" switch returns bare filenames in all caps).===
echo @echo off >zipup.bat
dir /b *.txt | sed "s/^\(.*\)\.TXT/pkzip -mo \1 \1.TXT/" >>zipup.bat
==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
;For additional syntax instructions, including the way to apply editing commands from a disk file instead of the command line, consult "sed & awk, 2nd Edition," by Dale Dougherty and Arnold Robbins (O'Reilly, 1997; http://www.ora.com), "UNIX Text Processing," by Dale Dougherty and Tim O'Reilly (Hayden Books, 1987) or the tutorials by Mike Arst distributed in U-SEDIT2.ZIP (many sites). To fully exploit the power of sed, one must understand "regular expressions." For this, see "Mastering Regular Expressions" by Jeffrey Friedl (O'Reilly, 1997). The manual ("man") pages on Unix systems may be helpful (try "man sed", "man regexp", or the subsection on regular expressions in "man ed"), but man pages are notoriously difficult. They are not written to teach sed use or regexps to first-time users, but as a reference text for those already acquainted with these tools.
==QUOTING SYNTAX:==
;The preceding examples use single quotes ('...') instead of double quotes ("...") to enclose editing commands, since sed is typically used on a Unix platform. Single quotes prevent the Unix shell from intrepreting the dollar sign ($) and backquotes (`...`), which are expanded by the shell if they are enclosed in double quotes. Users of the "csh" shell and derivatives will also need to quote the exclamation mark (!) with the backslash (i.e., \!) to properly run the examples listed above, even within single quotes. Versions of sed written for DOS invariably require double quotes ("...") instead of single quotes to enclose editing commands.
;USE OF '\t' IN SED SCRIPTS: For clarity in documentation, we have used the expression '\t' to indicate a tab character (0x09) in the scripts. However, most versions of sed do not recognize the '\t' abbreviation, so when typing these scripts from the command line, you should press the TAB key instead. '\t' is supported as a regular expression metacharacter in awk, perl, and in a few implementations of sed.
==VERSIONS OF SED:==
;Versions of sed do differ, and some slight syntax variation is to be expected. In particular, most do not support the use of labels (:name) or branch instructions (b,t) within editing commands, except at the end of those commands. We have used the syntax which will be portable to most users of sed, even though the popular GNU versions of sed allow a more succinct syntax. When the reader sees a fairly long command such as this:
sed -e '/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d
;it is heartening to know that GNU sed will let you reduce it to:
sed '/AAA/b;/BBB/b;/CCC/b;d'
;In addition, remember that while many versions of sed accept a command like "/one/ s/RE1/RE2/", some do NOT allow "/one/! s/RE1/RE2/", which contains space before the 's'. Omit the space when typing the command.
==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
;If you have any additional scripts to contribute or if you find errors in this document, please send e-mail to the compiler. Indicate the version of sed you used, the operating system it was compiled for, and the nature of the problem. Various scripts in this file were written or contributed by:
Al Aab <af137@freenet.toronto.on.ca> # "seders" list moderator
Dale Dougherty <dale@songline.com> # author of "sed & awk"
Carlos Duarte <cdua@algos.inesc.pt> # author of "do it with sed"
Eric Pement <epement@jpusa.chi.il.us> # author of this document
S.G.Ravenhall < S.G.Ravenhall@open.ac.uk> # great de-html script
Greg Ubben <gsu@romulus.ncsc.mil> # many contributions & much help
==Additional SED Commands==
===Lowercase to Upercase===
sed ’s/./\u&/g’
