Hide

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.


If you have a new feature suggestion or find a bug, please get in touch via http://commandlinefu.uservoice.com/

Get involved!

You can sign-in using OpenID credentials, or register a traditional username and password.

First-time OpenID users will be automatically assigned a username which can be changed after signing in.

Hide

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for:

Hide

News

2011-03-12 - Confoo 2011 presentation
Slides are available from the commandlinefu presentation at Confoo 2011: http://presentations.codeinthehole.com/confoo2011/
2011-01-04 - Moderation now required for new commands
To try and put and end to the spamming, new commands require moderation before they will appear on the site.
2010-12-27 - Apologies for not banning the trolls sooner
Have been away from the interwebs over Christmas. Will be more vigilant henceforth.
2010-09-24 - OAuth and pagination problems fixed
Apologies for the delay in getting Twitter's OAuth supported. Annoying pagination gremlin also fixed.
Hide

Tags

Hide

Functions

Commands tagged sed from sorted by
Terminal - Commands tagged sed - 327 results
sed -i '1s/^/text to prepend\n/' file1
2011-06-25 12:02:11
User: xeor
Functions: sed
Tags: sed replace
2

Using the sed -i (inline), you can replace the beginning of the first line of a file without redirecting the output to a temporary location.

sed -i 's/\r\n//' file.txt
gpg --refresh-keys
history | tail -(n+1) | head -(n) | sed 's/^[0-9 ]\{7\}//' >> ~/script.sh
2011-06-08 13:40:58
Functions: head sed tail
1

Uses history to get the last n+1 commands (since this command will appear as the most recent), then strips out the line number and this command using sed, and appends the commands to a file.

sed -n -e 1186,1210p A-small-practice.in
2011-06-04 10:53:46
User: evandrix
Functions: sed
Tags: sed
-1

Using sed to extract lines in a text file

If you write bash scripts a lot, you are bound to run into a situation where you want to extract some lines from a file. Yesterday, I needed to extract the first line of a file, say named somefile.txt.

cat somefile.txt

Line 1

Line 2

Line 3

Line 4

This specific task can be easily done with this:

head -1 somefile.txt

Line 1

For a more complicated task, like extract the second to third lines of a file. head is inadequate.

So, let's try extracting lines using sed: the stream editor.

My first attempt uses the p sed command (for print):

sed 1p somefile.txt

Line 1

Line 1

Line 2

Line 3

Line 4

Note that it prints the whole file, with the first line printed twice. Why? The default output behavior is to print every line of the input file stream.

The explicit 1p command just tells it to print the first line .... again.

To fix it, you need to suppress the default output (using -n), making explicit prints the only way to print to default output.

sed -n 1p somefile.txt

Line 1

Alternatively, you can tell sed to delete all but the first line.

sed '1!d' somefile.txt

Line 1

'1!d' means if a line is not(!) the first line, delete.

Note that the single quotes are necessary. Otherwise, the !d will bring back the last command you executed that starts with the letter d.

To extract a range of lines, say lines 2 to 4, you can execute either of the following:

sed -n 2,4p somefile.txt sed '2,4!d' somefile.txt

Note that the comma specifies a range (from the line before the comma to the line after).

What if the lines you want to extract are not in sequence, say lines 1 to 2, and line 4?

sed -n -e 1,2p -e 4p somefile.txt

Line 1

Line 2

Line 4

grep -E '<DT><A|<DT><H3' bookmarks.html | sed 's/<DT>//' | sed '/Bookmarks bar/d' | sed 's/ ADD_DATE=\".*\"//g' | sed 's/^[ \t]*//' | tr '<A HREF' '<a href'
2011-05-26 22:21:01
User: chrismccoy
Functions: grep sed tr
Tags: sed grep chrome
-1

chrome only lets you export in html format, with a lot of table junk, this command will just export the titles of the links and the links without all that extra junk

ls * | while read fin;do fout=$(echo -n $fin | sed -e's/%\([0-9A-F][0-9A-F]\)/\\\\\x\1/g' | xargs echo -e);if [ "$fout" != "$fin" ];then echo "mv '$fin' '$fout'";fi;done | bash -x
2011-05-18 07:24:54
User: pawelb1973
Functions: bash echo ls read sed xargs
0

urldecode files in current directrory

tcpdump -w "$(sed 's/-//gi; s/ /_/gi'<<<"-vvv -s0 -ieth1 -c10 icmp").pcap"
links -dump "http://spaceflight.nasa.gov/realdata/sightings/cities/view.cgi?country=United_States&region=Wisconsin&city=Portage" | sed -n '/--/,/--/p'
2011-05-03 12:15:56
User: eightmillion
Functions: sed
Tags: sed links iss
5

This command outputs a table of sighting opportunities for the International Space Station. Find the URL for your city here: http://spaceflight.nasa.gov/realdata/sightings/

sed 's/^#\(.*DEBUG\)/\1/' $FILE
ls -1 | sort -R | sed -n 's/^/Selected /;1p'
sed "s/^ *//;s/ *$//;s/ \{1,\}/ /g" filename.txt
2011-03-09 10:35:02
User: EBAH
Functions: sed
Tags: sed
1

The command removes all the spaces whithin a file and leaves only one space.

find . -maxdepth 1 -type d | grep -Pv "^.$" | sort -rn --field-separator="-" | sed -n '3,$p' | xargs rm -rf
echo -n "String to MD5" | md5sum | sed -e 's/../& /g' -e 's/ -//'
echo -n "String to MD5" | md5sum | sed -e 's/[0-9a-f]\{2\}/& /g' -e 's/ -//'
2011-03-05 11:47:08
User: saibbot
Functions: echo md5sum sed
Tags: sed md5sum
1

Generates the md5 hash, without the trailing " -" and with the output "broken" into pairs of hexs.

echo -n "String to get MD5" | md5sum | sed "s/ -//"
anagram(){ s(){ sed 's/./\n\0/g'<<<$1|sort;};cmp -s <(s $1) <(s $2)||echo -n "not ";echo anagram; }; anagram foobar farboo;
2011-02-17 15:10:43
User: bbbco
Functions: cmp echo sed
2

This is just a slight alternative that wraps all of #7917 in a function that can be executed

s(){ sed 's/./\n\0/g'<<<$1|sort;};cmp -s <(s foobar) <(s farboo)||echo -n "not ";echo anagram
2011-02-17 12:42:45
User: flatcap
Functions: cmp echo sed
-3

Are the two strings anagrams of one another?

sed splits up the strings into one character per line

the result is sorted

cmp compares the results

Note: This is not pretty. I just wanted to see if I could do it in bash.

Note: It uses fewer characters than the perl version :-)

seq 1 2 99999999 | sed 's!^!4/!' | paste -sd-+ | bc -l
2011-02-09 23:36:07
User: flatcap
Functions: bc paste sed seq
Tags: sed seq bc paste math
0

Calculate pi from the infinite series 4/1 - 4/3 + 4/5 - 4/7 + ...

This expansion was formulated by Gottfried Leibniz: http://en.wikipedia.org/wiki/Leibniz_formula_for_pi

I helped rubenmoran create the sum of a sequence of numbers and he replied with a command for the sequence: 1 + 2 -3 + 4 ...

This set me thinking. Transcendental numbers!

seq provides the odd numbers 1, 3, 5

sed turns them into 4/1 4/3 4/5

paste inserts - and +

bc -l does the calculation

Note: 100 million iterations takes quite a while. 1 billion and I run out of memory.

ifconfig eth3|sed 's/^eth3.*HWaddr //;q'
2011-02-09 00:22:40
User: avedis
Functions: ifconfig sed
Tags: sed
0

Just replace eth3 with the interface you want the MAC for.

Command in description (Your command is too long - please keep it to less than 255 characters)
2011-02-03 08:25:42
User: __
Functions: command less
0
yt2mp3(){ for j in `seq 1 301`;do i=`curl -s gdata.youtube.com/feeds/api/users/$1/uploads\?start-index=$j\&max-results=1|grep -o "watch[^&]*"`;ffmpeg -i `wget youtube.com/$i -qO-|grep -o 'url_map"[^,]*'|sed -n '1{s_.*|__;s_\\\__g;p}'` -vn -ab 128k "`youtube-dl -e ${i#*=}`.mp3";done;}

squeezed the monster (and nifty ☺) command from 7776 from 531 characters to 284 characters, but I don't see a way to get it down to 255. This is definitely a kludge!

curl -s 'http://www.discogs.com/search?q=724349691704' | sed -n '\#/release/#{s/^<div>.*>\(.*\)<\/a><\/div>/\1/p}'
2011-01-30 23:49:22
User: infinull
Functions: sed
Tags: sed discogs UPC
1

I like curl better than wget, I just think that curl -s is a lot simpler than wget ... see I forget what you even have to do to get wget to pipe it's output

Anyway, all in one sed command as "requested"

curl http://www.discogs.com/search?q=724349691704 2> /dev/null | grep \/release\/ | head -2 | tail -1 | sed -e 's/^<div>.*>\(.*\)<\/a><\/div>/\1/'
wget http://www.discogs.com/search?q=724349691704 -O foobar &> /dev/null ; grep \/release\/ foobar | head -2 | tail -1 | sed -e 's/^<div>.*>\(.*\)<\/a><\/div>/\1/' ; rm foobar
2011-01-30 23:34:54
User: TetsuyO
Functions: grep head rm sed tail wget
-1

Substitute that 724349691704 with an UPC of a CD you have at hand, and (hopefully) this oneliner should return the $Artist - $Title, querying discogs.com.

Yes, I know, all that head/tail/grep crap can be improved with a single sed command, feel free to send "patches" :D

Enjoy!

curl -s http://www.last.fm/user/$LASTFMUSER | grep -A 1 subjectCell | sed -e 's#<[^>]*>##g' | head -n2 | tail -n1 | sed 's/^[[:space:]]*//g'