sed '/^a test$/{ $!{ N # append the next line when not on the last line s/^a test\nPlease do not$/not a test\nBe/ # now test for a successful substitution, otherwise #+ unpaired "a test" lines would be mis-handled t sub-yes # branch_on_substitute (goto label :sub-yes) :sub-not # a label (not essential; here to self document) # if no substituion, print only the first line P # pattern_first_line_print D # pattern_ltrunc(line+nl)_top/cycle :sub-yes # a label (the goto target of the 't' branch) # fall through to final auto-pattern_print (2 lines) } }' alpha.txt

: # label = # line_number a # append_text_to_stdout_after_flush b # branch_unconditional c # range_change d # pattern_delete_top/cycle D # pattern_ltrunc(line+nl)_top/cycle g # pattern=hold G # pattern+=nl+hold h # hold=pattern H # hold+=nl+pattern i # insert_text_to_stdout_now l # pattern_list n # pattern_flush=nextline_continue N # pattern+=nl+nextline p # pattern_print P # pattern_first_line_print q # flush_quit r # append_file_to_stdout_after_flush s # substitute t # branch_on_substitute w # append_pattern_to_file_now x # swap_pattern_and_hold y # transform_chars

.---------------------------------------------------------------------. | | | UNIX Stream Editor | | Sed Cheat Sheet | | | '---------------------------------------------------------------------' | Created by Peter Krumins (peter@catonmat.net, @pkrumins on twitter) | | www.catonmat.net -- good coders code, great coders reuse | '---------------------------------------------------------------------' ==================== How Commands Affect Streams ==================== .---------.-----------.-----------------------------------------. | | | Modifications to: | | | Address '---------.---------.---------.-----------' | Command | or Range | Input | Output | Pattern | Hold | | | | Stream | Stream | Space | Buffer | '---------+-----------+---------+---------+---------+-----------' | = | - | - | + | - | - | | a | 1 | - | + | - | - | | b | 2 | - | - | - | - | | c | 2 | - | + | - | - | | d | 2 | + | - | + | - | | D | 2 | + | - | + | - | | g | 2 | - | - | + | - | | G | 2 | - | - | + | - | | h | 2 | - | - | - | + | | H | 2 | - | - | - | + | | i | 1 | - | + | - | - | | l | 1 | - | + | - | - | | n | 2 | + | * | - | - | | N | 2 | + | - | + | - | | p | 2 | - | + | - | - | | P | 2 | - | + | - | - | | q | 1 | - | - | - | - | | r | 1 | - | + | - | - | | s | 2 | - | - | + | - | | t | 2 | - | - | - | - | | w | 2 | - | + | - | - | | x | 2 | - | - | + | + | | y | 2 | - | - | + | - | '---------'-----------'---------'---------'---------'-----------' Modifications to: 1 Command takes single address or pattern. 2 Command takes pair of addresses. - Command does not modify the buffer. + Command modifies the buffer. * The ``n'' command may or may not generate output depending on the ``-n'' command option. ========================== Command Summary ========================== .----------------.----------------------------------------------------. | | | | Command | Description | | | | '----------------+----------------------------------------------------' | # | Adds a comment. | '----------------+----------------------------------------------------' | = | The "=" command prints the current line number to | | | standard output. | '----------------+----------------------------------------------------' | a \ | The "a" command appends text after the | | text | range or pattern. | '----------------+----------------------------------------------------' | b label | The "b" command branches to the label. You can | | | specify a label with a text string followed by a | | | colon. If no label is there, branch to the end of | | | the script. | '----------------+----------------------------------------------------' | c \ | The "c" command changes the current line with | | text | text. | '----------------+----------------------------------------------------' | d | The "d" command deletes the current pattern space, | | | reads in the next line, puts the new line into the | | | pattern space, and aborts the current command, and | | | starts execution at the first sed command. | '----------------+----------------------------------------------------' | D | The "D" command deletes the first portion of the | | | pattern space, up to the new line character, | | | leaving the rest of the pattern alone. | '----------------+----------------------------------------------------' | g | Instead of exchanging (the "x" command) the hold | | | space with the pattern space, you can copy the | | | hold space to the pattern space with the "g" | | | command. | '----------------+----------------------------------------------------' | G | If you want to append to the pattern space, use | | | the "G" command. | '----------------+----------------------------------------------------' | h | The "h" command copies the pattern buffer into the | | | hold buffer. | '----------------+----------------------------------------------------' | H | The "H" command allows you to combine several | | | lines in the hold buffer. It acts like the "N" | | | command as lines are appended to the buffer, with | | | a "\n" between the lines. You can save several | | | lines in the hold buffer, and print them only if a | | | particular pattern is found later. | '----------------+----------------------------------------------------' | i \ | You can insert text before the pattern with | | text | the "i" command. | '----------------+----------------------------------------------------' | l | The "l" command prints the current pattern space. | | | It is therefore useful in debugging sed scripts. | | | It also converts unprintable characters into | | | printing characters by outputting the value in | | | octal preceded by a "\" character. | '----------------+----------------------------------------------------' | n | The "n" command will print out the current pattern | | | space (unless the "-n" flag is used), empty the | | | current pattern space, and read in the next | | | line of input. | '----------------+----------------------------------------------------' | N | The "N" command does not print out the current | | | pattern space and does not empty the pattern | | | space. It reads in the next line, but appends a | | | new line character along with the input line | | | itself to the pattern space. | '----------------+----------------------------------------------------' | p | Another useful command is the print command: "p". | | | If sed wasn't started with an "-n" option, the "p" | | | command will duplicate the input. The "p" command | | | prints the entire pattern space. | '----------------+----------------------------------------------------' | P | The "P" command only prints the first part of the | | | pattern space, up to the NEWLINE character. | '----------------+----------------------------------------------------' | q | There is one more simple command that can restrict | | | the changes to a set of lines. It is the "q" | | | command: quit. This command is most useful when | | | you wish to abort the editing after some condition | | | is reached. | '----------------+----------------------------------------------------' | r filename | The "r" command will append text from filename | | | after the range or pattern. | '----------------+----------------------------------------------------' | s/regex/repl/ | The substitute command replaces all occurrences of | | | the regular expression (regex) with repl(acement) | '----------------+----------------------------------------------------' | t label | You can execute a branch if a pattern is found. | | | You may want to execute a branch only if a | | | substitution is made. The command "t label" will | | | branch to the label if the last substitute command | | | modified the pattern space. | '----------------+----------------------------------------------------' | w filename | With this command, you can specify a filename that | | | will receive the modified data. | '----------------+----------------------------------------------------' | x | The "x" command exchanges the hold buffer and the | | | pattern buffer. | '----------------+----------------------------------------------------' | y/source/dest/ | Transliterate the characters in the pattern space, | | | which appear in source to the corresponding | | | character in dest(ination). | '----------------'----------------------------------------------------' ======================== Command Extensions ========================= .----------------.----------------------------------------------------. | | | | Command | Description | | | | '----------------+----------------------------------------------------' | Q | Immediately quit the sed script without processing | | | any more input. (zero or one address command) | '----------------+----------------------------------------------------' | R filename | Append a line read from filename. (zero or one | | | address command). | '----------------+----------------------------------------------------' | T label | If no s/// has done a successful substitution | | | since the last input line was read and since the | | | last t or T command, then branch to label; | | | if label is omitted, branch to end of script. | | | (accepts address range). | '----------------+----------------------------------------------------' | W filename | Write the first line of the current pattern space | | | to filename. (accepts address range). | '----------------'----------------------------------------------------' ======================= Address Range Summary ======================= .----------------.----------------------------------------------------. | | | | Format | Description | | | | '----------------+----------------------------------------------------' | number | Match only the specified line number. | '----------------+----------------------------------------------------' | first~step | Match every step'th line starting with line first. | '----------------+----------------------------------------------------' | $ | Match the last line. | '----------------+----------------------------------------------------' | 0, addr2 | Start out in "matched first address" state, | | | until addr2 is found. | '----------------+----------------------------------------------------' | /regex/ | Match lines matching the regular expression regex. | '----------------+----------------------------------------------------' | addr1,+N | Will match addr1 and the N lines following addr1. | '----------------+----------------------------------------------------' | \cregexc | Match lines matching the regular expression regex. | | | The c may be any character. | '----------------+----------------------------------------------------' | addr1,~N | Will match addr1 and the lines following addr1 | | | until the next line whose input line number | | | is a multiple of N. | '----------------'----------------------------------------------------' ============== GNU Sed's Command Line Argument Summary ============== .---------------------.-----------------------------------------------. | | | | Argument | Description | | | | '---------------------+-----------------------------------------------' | -n | | | --quiet | Suppress automatic printing of pattern space. | | --silent | | '---------------------+-----------------------------------------------' | -e script | | | --expression=script | Add the script to the commands to be executed.| | | | '---------------------+-----------------------------------------------' | -f script-file | Add the contents of script-file to the | | --file=script-file | commands to be executed. | '---------------------+-----------------------------------------------' | -i[suffix] | Sdit files in place (makes backup if | | --in-place[=suffix] | extension supplied). | '---------------------+-----------------------------------------------' | -l N | Specify the desired line-wrap length for | | --line-length=N | the `l' command. | '---------------------+-----------------------------------------------' | -r | Use extended regular expressions in the | | --regexp-extended | script. | '---------------------+-----------------------------------------------' | -s | Consider files as separate rather than as a | | --separate | single continuous long stream. | '---------------------+-----------------------------------------------' | -u | Load minimal amounts of data from the input | | --unbuffered | files and flush the output buffers more often.| '---------------------+-----------------------------------------------' | --help | Display this help and exit | '---------------------+-----------------------------------------------' | -V | Output version information and exit | | --version | | '---------------------'-----------------------------------------------' ===================================================================== .---------------------------------------------------------------------. | Created by Peter Krumins (peter@catonmat.net, @pkrumins on twitter) | | www.catonmat.net -- good coders code, great coders reuse | '---------------------------------------------------------------------'

Sed by example

sed gets input stream (usually file) line by line, modify each line accordingly to rules in sed's script file and print the result to output stream.

Following is example of command

sed [options] '{script}' [file(s)]

If there is no file as input then sed reads input stream or pipeline. If you want the result in a text file, you can either redirect it via the regular method:

sed [options] '{script}' [inputfile] > [output]

Or use the option -i that will directly edit the input file

sed -i [options] '{script}' [inputfile]

Search
Command     Description
sed -n "3p" file.txt    print 3rd line
sed -n '1,3p' file.txt  print strings from 1st to 3rd
sed -n "/[media]/,/[public]/p" smb.conf     print strings from 1st to 3rd which contains specified string
sed -n '/[media]/,$p' smb.conf  print strings from first mention of media till end of file
sed 5,15d file.txt  show all of file.txt except for lines from 5 to 15
sed '/pattern/q' file.txt   print all lines till pattern
sed -n '/pattern/p' file.txt    print do matched strings (emulates grep)
sed -n '/pattern/!p' file.txt   print do NOT matched strings (emulates grep -v)
sed -n 's/unix/linux/p' file.txt    printing only the replaced lines
sed -n '/X/!p' file.txt     print lines which does not contain 'X'
sed -n '2~5p' file.txt  print every 5th line starting with the second
sed '/AAA.*BBB.*CCC/!d' file.txt    grep for AAA and BBB and CCC (in that order)
sed '/AAA/!d; /BBB/!d; /CCC/!d' file.txt    grep for AAA and BBB and CCC (in any order)

Modify
Command     Description
sed 's/foo/boo/' file.txt   replace first entrance foo with boo
sed 's|http://|www|' file.txt   replace first entrance foo with boo (another divider)
sed 's/foo/boo/g' file.txt  replace all entrances foo with boo
sed 's/foo/boo/3' file.txt  replace first three entrances foo with boo
sed 's/foo/[&]/' file.txt   wrap foo with [ ]
sed 's/pattern1|pattern2/foo/g' file.txt    replace pattern1 or pattern2 with foo
sed 's/\(foo\)\(boo\)/\2\1/' file.txt   replace fooboo with boofoo
sed 's/^../XX/' file.txt    replace the first two characters of a string or a line with "XX"
sed -e 's/unix/linux/' -e 's/os/system/' file.txt   -e option provieds to run multiple sed commands in a single sed command
sed '3 s/foo/boo/' file.txt     replace string on a specific line number
sed '1,3 s/foo/boo/' file.txt   replace string on a range of lines
sed '/pattern/ s/foo/boo/' file.txt     replace on a lines which matches a pattern
sed '1i HEAD1, HEAD2' file.txt  insert a header line
sed -i '1a -------' file.txt    add a line '-------' at the 1st line
sed '5!s/foo/boo/' file.txt     replace foo with boo in file.txt except in the 5th line
sed '/pattern/!s/foo/boo/' file.txt     unless pattern is found replace foo with boo
sed '/pattern/s/foo/boo/g' file.txt     only if line contains pattern, substitute foo with boo
sed '1d;$d' file.txt    delete the first line AND the last line of a file
sed '/^$/d' file.txt    delete all blank lines in the file
sed '/foo/,$d' file.txt     delete the lines starting from the pattern 'foo' till the last line
sed '1,4{/foo/d;}' file.txt     delete the lines containing the pattern 'foo' only if it is present in the lines from 1 to 4
sed '1,20 s/foo/boo/g' file.txt     replace foo with boo only on lines between 1 and 20
sed '1,20 !s/foo/boo/g' file.txt    the above reversed (match all except lines 1-20)
sed '/pattern/G' file.txt   insert blank line below every line that match pattern
sed 'n;n;n;n;G;' file.txt   add a blank line every 5 lines (after lines 5, 10, 15, 20, etc.)
sed 's/^/ /' file.txt   insert 5 blank spaces at beginning of each line (make page offset)
sed '/foo/ a "boo"' file.txt    add a line after a match
sed '/foo/ i "boo"' file.txt    add a line before a match
sed '/foo/ c "boo"' file.txt    replace an entire line with a new line
sed ‘s/^/\t/’ file.txt  insert a tab at beginning of each line
sed -e 's/#.*//' file.txt   delete all the comment lines from a file
$sed 's/.$//' file.txt  convert DOS newlines (CR/LF) to Unix format
sed -e '$r 2.txt' 1.txt     insert file 2.txt at the end of 1.txt
sed 's/\t/ /g' file.txt     replace tab with spaces
find ~/projects/ -type f -exec sed -i 's/nodejs/django/g' {} \;     replace in all found files
find ~/projects/ -name "*.js" -print | xargs sed -i 's/nodejs/django/g'     replace in multiple files

Delete
Command     Description
sed -n "3,10d" file.txt     delete all lines from line 3 till 10
sed '17,/foo/d' file.txt    delete all lines from line 17 to 'foo'
sed 's/^[ ^t]*//' file.txt  delete all spaces in front of every line of file.txt
sed 's/[ ^t]*$//' file.txt  delete all spaces at the end of every line of file.txt
sed 's/^[ ^t]*//;s/[ ^]*$//' file.txt   delete all spaces in front and at the end of every line of file.txt
sed '1~3d' file.txt     delete every third line, starting with the first
sed ‘/^$/d’ in.txt > out.txt    delete all the blank lines from a file
sed '0,/pattern_to_delete/{//d;}' file.txt  delete only first match from a file