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 awk from sorted by
Terminal - Commands tagged awk - 294 results
tar -cf - . | pv -s $(du -sb . | awk '{print $1}') | gzip > out.tgz
2009-12-18 17:09:08
User: opertinicy
Functions: awk du gzip tar
25

What happens here is we tell tar to create "-c" an archive of all files in current dir "." (recursively) and output the data to stdout "-f -". Next we specify the size "-s" to pv of all files in current dir. The "du -sb . | awk ?{print $1}?" returns number of bytes in current dir, and it gets fed as "-s" parameter to pv. Next we gzip the whole content and output the result to out.tgz file. This way "pv" knows how much data is still left to be processed and shows us that it will take yet another 4 mins 49 secs to finish.

Credit: Peteris Krumins http://www.catonmat.net/blog/unix-utilities-pipe-viewer/

curl -sL 'dynamic.xkcd.com/comic/random/' | awk -F\" '/^<img/{printf("<?xml version=\"1.0\"?>\n<xkcd>\n<item>\n <title>%s</title>\n <comment>%s</comment>\n <image>%s</image>\n</item>\n</xkcd>\n", $6, $4, $2)}'
wget -q http://dynamic.xkcd.com/comic/random/ -O-| sed -n '/<img src="http:\/\/imgs.xkcd.com\/comics/{s/.*\(http:.*\)" t.*/\1/;p}' | awk '{system ("wget -q " $1 " -O- | display -title $(basename " $1") -write /tmp/$(basename " $1")");}'
2009-12-09 13:41:25
User: laugg
Functions: awk sed wget
Tags: sed awk wget comic
0

Only need to install Image Magick package.

Display a xkcd comic with its title and save it in /tmp directory

If you prefer to view the newest xkcd, use this command:

wget -q http://xkcd.com/ -O-| sed -n '/<img src="http:\/\/imgs.xkcd.com\/comics/{s/.*\(http:.*\)" t.*/\1/;p}' | awk '{system ("wget -q " $1 " -O- | display -title $(basename " $1") -write /tmp/$(basename " $1")");}'
curl -s 'xkcd.com' | awk -F\" '/^<img/{printf("<?xml version=\"1.0\"?>\n<xkcd>\n<item>\n <title>%s</title>\n <comment>%s</comment>\n <image>%s</image>\n</item>\n</xkcd>\n", $6, $4, $2)}'
2009-12-03 19:49:37
User: putnamhill
Functions: awk
0

I wasn't sure how to display the image, so I thought I'd try xml for a different twist.

awk '/q=/{print $11}' /var/log/httpd/access_log.4 | awk -F 'q=' '{print $2}' | sed 's/+/ /g;s/%22/"/g;s/q=//' | cut -d "&" -f 1
cat /var/log/httpd/access_log | grep q= | awk '{print $11}' | awk -F 'q=' '{print $2}' | sed 's/+/ /g;s/%22/"/g;s/q=//' | cut -d "&" -f 1 | mail youremail@isp.com -s "[your-site] search strings for `date`"
2009-11-22 03:03:06
User: isma
Functions: awk cat grep sed strings
-2

It's not a big line, and it *may not* work for everybody, I guess it depends on the detail of access_log configuration in your httpd.conf. I use it as a prerotate command for logrotate in httpd section so it executes before access_log rotation, everyday at midnight.

albumart(){ local y="$@";awk '/View larger image/{gsub(/^.*largeImagePopup\(.|., .*$/,"");print;exit}' <(curl -s 'http://www.albumart.org/index.php?srchkey='${y// /+}'&itempage=1&newsearch=1&searchindex=Music');}
2009-11-15 19:54:16
User: eightmillion
7

This bash function uses albumart.org to find the cover for an album. It returns an amazon.com url to the image.

Usage: albumart [artist] [album]

These arguments can be reversed and if the album name is distinct enough, it may be possible to omit the artist.

The command can be extended with wget to automatically download the matching image like this:

albumart(){ local x y="$@";x=$(awk '/View larger image/{gsub(/^.*largeImagePopup\(.|., .*$/,"");print;exit}' <(curl -s 'http://www.albumart.org/index.php?srchkey='${y// /+}'&itempage=1&newsearch=1&searchindex=Music'));[ -z "$x" ]&&echo "Not found."||wget "$x" -O "${y}.${x##*.}";}
ompload() { curl -# -F file1=@"$1" http://ompldr.org/upload|awk '/Info:|File:|Thumbnail:|BBCode:/{gsub(/<[^<]*?\/?>/,"");$1=$1;print}';}
2009-11-07 20:56:52
User: eightmillion
Functions: awk
8

This function uploads images to http://omploader.org and then prints out the links to the file.

Some coloring can also be added to the command with:

ompload() { curl -F file1=@"$1" http://omploader.org/upload|awk '/Info:|File:|Thumbnail:|BBCode:/{gsub(/<[^<]*?\/?>/,"");$1=$1;sub(/^/,"\033[0;34m");sub(/:/,"\033[0m:");print}';}
ifconfig | awk '/HW/ {print $5}'
2009-11-05 18:00:50
User: Cont3mpo
Functions: awk ifconfig
0

Simple MAC adrress, thanks to ifconfig.

svn ci `svn stat |awk '/^A/{printf $2" "}'`
ifconfig eth1 | grep inet\ addr | awk '{print $2}' | cut -d: -f2 | sed s/^/eth1:\ /g
2009-11-03 19:26:40
User: TuxOtaku
Functions: awk cut grep ifconfig sed
2

Sometimes, you don't really care about all the other information that ifconfig spits at you (however useful it may otherwise be). You just want an IP. This strips out all the crap and gives you exactly what you want.

awk 'BEGIN {for(i=1;i<=100;i++)sum+=i}; END {print sum}' /dev/null
2009-10-26 18:24:57
User: dennisw
Functions: awk
Tags: awk
0

Calculating series with awk only, no need for seq: add numbers from 1 to 100

Variations:

1+3+...+(2n-1) = n^2

awk 'BEGIN {for(i=1;i<=19;i+=2)sum+=i}; END {print sum}' /dev/null # displays 100

1/2 + 1/4 + ... = 1

awk 'BEGIN {for(i=1;i<=10;i++)sum+=1/(2**i)}; END {print sum}' /dev/null # displays 0.999023
awk 'BEGIN{dir=DIR?DIR:ENVIRON["PWD"];l=split(dir,parts,"/");last="";for(i=1;i<l+1;i++){d=last"/"parts[i];gsub("//","/",d);system("ls -ld \""d"\"");last=d}}'
2009-10-22 16:28:07
User: arcege
Functions: awk
-1

Handled all within awk. Takes the value from $PWD and constructs directory structures and runs commands against them. The gsub() call is not necessary, but added for better visibility.

If a variable DIR is given on the awk command-line, then that directory is used instead:

awk -vDIR=$HOME/.ssh 'BEGIN{dir=DIR?...}'
(echo "set terminal png;plot '-' u 1:2 t 'cpu' w linespoints;"; sudo vmstat 2 10 | awk 'NR > 2 {print NR, $13}') | gnuplot > plot.png
vmstat 2 10 | awk 'NR > 2 {print NR, $13}' | gnuplot -e "set terminal png;set output 'v.png';plot '-' u 1:2 t 'cpu' w linespoints;"
find $HOME -type f -print0 | perl -0 -wn -e '@f=<>; foreach $file (@f){ (@el)=(stat($file)); push @el, $file; push @files,[ @el ];} @o=sort{$a->[9]<=>$b->[9]} @files; for $i (0..$#o){print scalar localtime($o[$i][9]), "\t$o[$i][-1]\n";}'|tail
2009-09-21 22:11:16
User: drewk
Functions: find perl
3

This pipeline will find, sort and display all files based on mtime. This could be done with find | xargs, but the find | xargs pipeline will not produce correct results if the results of find are greater than xargs command line buffer. If the xargs buffer fills, xargs processes the find results in more than one batch which is not compatible with sorting.

Note the "-print0" on find and "-0" switch for perl. This is the equivalent of using xargs. Don't you love perl?

Note that this pipeline can be easily modified to any data produced by perl's stat operator. eg, you could sort on size, hard links, creation time, etc. Look at stat and just change the '9' to what you want. Changing the '9' to a '7' for example will sort by file size. A '3' sorts by number of links....

Use head and tail at the end of the pipeline to get oldest files or most recent. Use awk or perl -wnla for further processing. Since there is a tab between the two fields, it is very easy to process.

ls -t | awk 'NR>5 {system("rm \"" $0 "\"")}'
2009-09-16 04:58:08
User: haivu
Functions: awk ls
Tags: awk ls
-2

I have a directory containing log files. This command delete all but the 5 latest logs. Here is how it works:

* The ls -t command list all files with the latest ones at the top

* The awk's expression means: for those lines greater than 5, delete.

awk '{delta = $1 - avg; avg += delta / NR; mean2 += delta * ($1 - avg); } END { print sqrt(mean2 / NR); }'
2009-09-11 04:46:01
User: ashawley
Functions: awk delta
Tags: awk
4

This will calculate a running standard deviation in one pass and should never have the possibility for overflow that can happen with other implementations. I suppose there is a potential for underflow in the corner case where the deltas are small or the values themselves are small.

awk 'length>72' file
2009-09-10 05:54:41
User: haivu
Functions: awk
Tags: awk
16

This command displays a list of lines that are longer than 72 characters. I use this command to identify those lines in my scripts and cut them short the way I like it.

echo src::${PATH} | awk 'BEGIN{pwd=ENVIRON["PWD"];RS=":";FS="\n"}!$1{$1=pwd}$1!~/^\//{$1=pwd"/"$1}{print $1}'
2009-09-09 04:03:46
User: arcege
Functions: awk echo
Tags: awk echo PATH
-2

Removes trailing newline; colon becomes record separator and newline becomes field separator, only the first field is ever printed. Replaces empty entries with $PWD. Also prepend relative directories (like ".") with the current directory ($PWD). Can change PWD with env(1) to get tricky in (non-Bourne) scripts.

find . -name \*.c | xargs wc -l | tail -1 | awk '{print $1}'
2009-09-08 08:25:45
User: karpoke
Functions: awk find tail wc xargs
Tags: awk find wc
0

This is really fast :)

time find . -name \*.c | xargs wc -l | tail -1 | awk '{print $1}'

204753

real 0m0.191s

user 0m0.068s

sys 0m0.116s

curl -u username:password --silent "https://mail.google.com/mail/feed/atom" | tr -d '\n' | awk -F '<entry>' '{for (i=2; i<=NF; i++) {print $i}}' | sed -n "s/<title>\(.*\)<\/title.*name>\(.*\)<\/name>.*/\2 - \1/p"
2009-09-07 21:56:40
User: postrational
Functions: awk sed tr
42

Checks the Gmail ATOM feed for your account, parses it and outputs a list of unread messages.

For some reason sed gets stuck on OS X, so here's a Perl version for the Mac:

curl -u username:password --silent "https://mail.google.com/mail/feed/atom" | tr -d '\n' | awk -F '<entry>' '{for (i=2; i<=NF; i++) {print $i}}' | perl -pe 's/^<title>(.*)<\/title>.*<name>(.*)<\/name>.*$/$2 - $1/'

If you want to see the name of the last person, who added a message to the conversation, change the greediness of the operators like this:

curl -u username:password --silent "https://mail.google.com/mail/feed/atom" | tr -d '\n' | awk -F '<entry>' '{for (i=2; i<=NF; i++) {print $i}}' | perl -pe 's/^<title>(.*)<\/title>.*?<name>(.*?)<\/name>.*$/$2 - $1/'
awk 'BEGIN {a=1;b=1;for(i=0;i<'${NUM}';i++){print a;c=a+b;a=b;b=c}}'
2009-09-06 03:05:55
User: arcege
Functions: awk
Tags: awk
0

Does not require input to function or complete. Number of iterations controlled by shell variable $NUM.

find . -type f -name '*.c' -exec wc -l {} \; | awk '{sum+=$1} END {print sum}'
2009-09-04 15:51:30
User: arcege
Functions: awk find wc
Tags: awk find wc
-1

Have wc work on each file then add up the total with awk; get a 43% speed increase on RHEL over using "-exec cat|wc -l" and a 67% increase on my Ubuntu laptop (this is with 10MB of data in 767 files).

find . -exec grep foobar /dev/null {} \; | awk -F: '{print $1}' | xargs vi