sed (stream editor) is a Unix utility that parses and transforms text, using a simple, compact programming language. (wiki)
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 |
Useful links