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.

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.

UpGuard checks and validates configurations for every major OS, network device, and cloud provider.

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:



May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

Top Tags



Commands using seq from sorted by
Terminal - Commands using seq - 89 results
for i in $(seq 1 `curl http://megatokyo.com 2>/dev/null|grep current|cut -f6 -d\"`);do wget http://megatokyo.com/`curl http://megatokyo.com/strip/${i} 2>/dev/null|grep src=\"strips\/|cut -f4 -d\"`;done
2012-03-04 22:52:36
User: akira88
Functions: cut grep seq wget
Tags: wget comic

A simple script for download all the MegaTokyo strips from the first to the last one

pktsize=1516;for i in $( seq $pktsize -8 1450 ) ; do ping -M do -s $i -c 1 slashdot.org; done
2012-02-21 01:58:07
Functions: ping seq

Linux - starting with a packetsize that must be split into two packets, count down by 8 bytes, and try to send the packet using the "Don't Fragment" option. The actual MTU (the size of the actual PING packet) is (in this example) 1460 data bytes + 20 bytes IP header + 8 bytes PING request = 1488

sayspeed() { for i in $(seq 1 `echo "$1"|wc -c`); do echo -n "`echo $1 |cut -c ${i}`"; sleep 0.1s; done; echo "";}
2012-02-11 05:51:42
User: kundan
Functions: echo seq sleep wc

change the time that you would like to have as print interval

and just use it to say whatever you want to

enscript -L1 -b'||Page $% of $=' -o- < <(for i in $(seq "$(pdftk "$1" dump_data | grep "Num" | cut -d":" -f2)"); do echo; done) | ps2pdf - | pdftk "$1" multistamp - output "${1%.pdf}-header.pdf"
2012-01-27 12:26:33
User: captaincomic
Functions: seq

Put this code in a bash script. The script expects the PDF file as its only parameter.

It will add a header to the PDF containing the page numbers and output it to a file with the suffix "-header.pdf"

Requires enscript, ps2pdf and pdftk.

genRandomText() { a=( a b c d e f g h i j k l m n o p q r s t u v w x y z );f=0;for i in $(seq 1 $(($1-1))); do r=$(($RANDOM%26)); if [ "$f" -eq 1 -a $(($r%$i)) -eq 0 ]; then echo -n " ";f=0;continue; else f=1;fi;echo -n ${a[$r]};done;echo"";}
2012-01-20 21:18:16
User: bbbco
Functions: echo seq

Ever need to get some text that is a specific number of characters long? Use this function to easily generate it! Doesn't look pretty, but sure does work for testing purposes!

comm -13 <(od -vw1 -tu1 dummy.txt|cut -c9-|sort -u) <(seq 0 127|sort)|perl -pe '$_=chr($_)'|od -c
2012-01-09 01:32:20
User: bazzargh
Functions: comm cut od perl seq sort
Tags: bash

Search in decimal rather than hex. od dumps the character list, cut to remove offsets, sort -u gives the used characters. seq gives the comparison list, but we need this sorted alphabetically for comm, which does the filtering. I drop to perl to convert back to characters (is there a better way?) and then use od to dump them in a print-safe format.

seq 1 3 20 | awk '{ T[NR]=$1} END {for (i=1;i<=(NR-1);i++) print T[i+1],"-",T[i],"=" , T[i+1]-T[i]}'
2011-11-13 10:36:18
User: benoit_c_lbn
Functions: awk seq
Tags: sed

It's allways strange for me to see sed and awk in the same command line if you can avoid it

seq 1 3 20 | sed -n '1{h;d};H;x;s/\n/\t/p' | awk '{printf("%d - %d = %d\n", $2, $1, $2-$1)}'
seq 9 | sed 'H;g' | awk -v RS='' '{for(i=1;i<=NF;i++)printf("%dx%d=%d%s", i, NR, i*NR, i==NR?"\n":"\t")}'
2011-10-22 18:41:09
User: kev
Functions: awk sed seq
Tags: sed awk

seq -s ' ' 1 9 | sed -n ':a;p;s/ *\w$//;h;/^$/t;b a;q' | tac | awk '{for(i=1;i


1x2=2 2x2=4

1x3=3 2x3=6 3x3=9

1x4=4 2x4=8 3x4=12 4x4=16

1x5=5 2x5=10 3x5=15 4x5=20 5x5=25

1x6=6 2x6=12 3x6=18 4x6=24 5x6=30 6x6=36

1x7=7 2x7=14 3x7=21 4x7=28 5x7=35 6x7=42 7x7=49

1x8=8 2x8=16 3x8=24 4x8=32 5x8=40 6x8=48 7x8=56 8x8=64

1x9=9 2x9=18 3x9=27 4x9=36 5x9=45 6x9=54 7x9=63 8x9=72 9x9=81

seq 20 | sed '5,6 { w out.txt }' #Can't print correctly. See sample output
2011-08-29 10:17:47
User: totti
Functions: sed seq
Tags: sed

Can't print correctly in the command field.

There is a new line before } as follows

seq 20 | sed -n '5,6 { w out.txt


parallel -a <(seq 0 20) mkdir /tmp/dir1/{}
seq 1 255 | parallel -j+0 'nc -w 1 -z -v 192.168.1.{} 80'
2011-06-11 14:40:51
User: devrick0
Functions: seq

It takes over 5 seconds to scan a single port on a single host using nmap

time (nmap -p 80 &> /dev/null)

real 0m5.109s

user 0m0.102s

sys 0m0.004s

It took netcat about 2.5 minutes to scan port 80 on the class C

time (for NUM in {1..255} ; do nc -w 1 -z -v 192.168.1.${NUM} 80 ; done &> /dev/null)

real 2m28.651s

user 0m0.136s

sys 0m0.341s

Using parallel, I am able to scan port 80 on the entire class C in under 2 seconds

time (seq 1 255 | parallel -j255 'nc -w 1 -z -v 192.168.1.{} 80' &> /dev/null)

real 0m1.957s

user 0m0.457s

sys 0m0.994s

seq 20 | awk 'ORS=NR%5?FS:RS'
2011-05-26 11:39:34
User: kev
Functions: awk seq
Tags: awk

seq 20 | awk '{line=line sep $0; sep=" "} !(NR%5){print line; line=sep=""}'

MIN=10 && for i in $(seq $(($MIN*60)) -1 1); do printf "\r%02d:%02d:%02d" $((i/3600)) $(( (i/60)%60)) $((i%60)); sleep 1; done
seq -s "+" 3 | bc
seq -f"%g^2" -s "+" 10 | bc
echo $(($(seq -s* 10)))
2011-02-10 18:44:53
User: minduim
Functions: echo seq
Tags: math factorial

Same as the seq/bc solution but without bc.

seq -s^2+ 11 |rev| cut -d'+' -f2- | rev | bc
2011-02-10 08:41:14
User: rubenmoran
Functions: cut rev seq
Tags: seq sum math

I can't put the last ^2 with seq, so I reverse it to delete the last +N. So for doing sum(N^2) you have to do sum((N+1)^2). Must be a better way.

seq -s* 10 |bc
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

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.

seq 1000 | paste -sd+- | bc
seq 10 | paste -sd* | bc
seq 100000 | paste -sd+ | bc
seq -w 50 | sort -R | head -6 |fmt|tr " " "-"
(netstat -atn | awk '{printf "%s\n%s\n", $4, $4}' | grep -oE '[0-9]*$'; seq 32768 61000) | sort -n | uniq -u | head -n 1