================================================================================ #Join lines ipsecconf | grep -v ^$ | sed 'N;s/\n//' ================================================================================ NAME sed-tutorial - a small tutorial about sed DESCRIPTION sed(1) is a non-interactive text editor that comes with UNIX since Version 7 AT&T UNIX. It's main purpose is to be used in scripts. SIMPLE TEXT EDITING sed(1) works as a filter, which makes it particularly useful for scripts. sed(1) works line oriented. The most simple commands are a pattern and an action. If no pattern is given, the action is applied to all lines, otherwise it is applied only to lines matching the pattern. Line-oriented Patterns A sample application of sed(1) would be to delete the first 10 lines of stdin and echo the rest to stdout: sed -e '1,10d' The -e tells sed to execute the next command line argument as sed program. Since sed programs often contain regular expressions, they will often contain characters that your shell interprets, so you should get used to put all sed programs in single quotes so your shell won't interpret the sed program. In this case, nothing bad would have happened, but since almost all other examples will contain meta-characters, you really should get used to quoting your programs. This simple sed program contains a pattern (``1,10'') and an action (``d''). What sed(1) does is apply all actions whose pattern match and finally print the line unless the action was ``d''. If you don't want sed(1) to print each line by default, you can give sed the -n option. Then only lines that you print explicitly (with the ``p'' action) appear on stdout. If we wanted to print only the first ten lines, we would have deleted all the lines starting with 11: sed -e '11,$d' Note that $ is the last line. Because sed(1) processes the input line by line, it does not keep the whole input in memory. This makes sed(1) very useful for processing large files, but it has it's drawbacks, too. For example, we can't use sed -e '$-10,$d', since sed doesn't know $ before the end of file, so it doesn't know where $-10 is. This is a major problem, and it limits sed(1)'s usefulness, but sed(1) still has a large number of appliances. Another way to get only the first 10 lines is to use the -n option: sed -n -e '1,10p' If we want to delete only one line, the pattern can be '10,10' or simple '10'. More Than One Command Commands in sed(1) programs are separated by new lines. So if we wanted to delete the lines 1 to 4 and 6 to 9, we could use: sed -e '1,4d 6,9d' Another possibility is to use the -e option more than once: sed -e '1,4d' -e '6,9d' That's why we used the -e option all the time. In fact, you can omit it if you have only one command in your program. But you should get used to the -e option, so you won't have to add it if you want to extend your program later on. Regular Expression Oriented Patterns Often, we don't know the numbers of the lines we want to delete. A good example is a log file. Log files tend to grow until they become too large to handle. Let's assume that you have a large log file called log which contains thousands of lines. Now you want to delete all the lines that contain the word ``debug'': sed -e '/debug/d' < log This works just like grep -v debug. A Slightly More Complex Example We are still working with the large log file. Now we not only want to delete lines with the word debug, but we only want lines that contain ``foo''. The traditional way to handle this would be: grep 'foo' < log | grep -v debug Note that this spawns two grep processes. The sed equivalent would be: sed -n -e '/debug/d' -e '/foo/p' You might wonder why lines with debug aren't printed if they contain foo. The answer is that the ``d'' action skips the rest of the patterns and actions, too, it does not just inhibit the print in the end (which is inhibited here due to the -n, anyway). Putting sed Programs Into Files Now that your programs are getting a little more advanced, you might want to put them in script files instead of using the command line. To tell sed(1) about your program file, you use the -f option: sed -f program.sed There is a kludge in sed(1) that allows you to set the -n option from within your sed program if you use ``#n'' as the first line in your program file. From now on I will assume that you run the examples through sed -f. Inserting Text You can insert text with the ``a'' and ``i'' actions. The syntax is: 10i\ string to be inserted The difference between ``i'' and ``a'' is that ``i'' inserts before the current line and ``a'' appends after the current line. So ``1i'' will insert before the first line and ``$a'' will append after the last line. Replacing the current line You can replace the current line with the ``c'' action. The syntax is like ``i'' and ``a'': 10c\ new contents for line 10 Printing The Current Line Visually Unambiguously The ``l'' action is very useful when editing files with nonprintable characters. It prints the current line visually unambiguously. For example, long lines are broken, but the lines end with a \ to show that they were broken. Normal backslashes in the text are escaped, too, tabs are replaced with \t and nonprintable characters are printed as escaped three-digit octal numbers. This example is quite useful as shell alias: sed -n -e 'l' Aborting Processing The ``q'' action branches to the end of the script and ends the script processing after this line. So, yet another way of printing the first 10 lines would have been: sed -e '10q' REGULAR EXPRESSION SUBSTITUTION The ``s/pattern/replacement/[flags]'' action is the most often used sed(1) action. In fact, most sed programs consist only of substitute commands, since this is so immensely useful. The regular expression pattern is substituted by the replacement string (which can contain several special symbols). The most basic substitution would be sed -e 's/foo/bar/' which would just change the string ``foo'' to ``bar''. SEE ALSO sed(1), awk(1), mawk(1), nawk(1), gawk(1) ================================================================================ HANDY ONE-LINERS FOR SED (Unix stream editor) Oct. 29, 1997 compiled by Eric Pement version 4.3 Latest version of this file is always at 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;/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: ================================================================================ UNIX | SED -------------+---------------------------------------------------------------- cat | sed ':' cat -s | sed '/./,/^$/!d' tac | sed '1!G;h;$!d' grep | sed '/patt/!d' grep -v | sed '/patt/d' head | sed '10q' head -1 | sed 'q' tail | sed -e ':a' -e '$q;N;11,$D;ba' tail -1 | sed '$!d' tail -f | sed -u '/./!d' cut -c 10 | sed 's/\(.\)\{10\}.*/\1/' cut -d: -f4 | sed 's/\(\([^:]*\):\)\{4\}.*/\2/' tr A-Z a-z | sed 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/' tr a-z A-Z | sed 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/' tr -s ' ' | sed 's/ \+/ /g' tr -d '\012' | sed 'H;$!d;g;s/\n//g' wc -l | sed -n '$=' uniq | sed 'N;/^\(.*\)\n\1$/!P;D' rev | sed '/\n/!G;s/\(.\)\(.*\n\)/&\2\1/;//D;s/.//' basename | sed 's,.*/,,' dirname | sed 's,[^/]*$,,' xargs | sed -e ':a' -e '$!N;s/\n/ /;ta' paste -sd: | sed -e ':a' -e '$!N;s/\n/:/;ta' cat -n | sed '=' | sed '$!N;s/\n/ /' grep -n | sed -n '/patt/{=;p;}' | sed '$!N;s/\n/:/' cp orig new | sed 'w new' orig ================================================================================