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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!

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Psst. Open beta.

Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:

  • » The open beta is running a copy of the database that will not carry over to the final version. Don't post anything you don't mind losing.
  • » If you wish to use your user account, you will probably need to reset your password.
Your feedback is appreciated via the form on the beta page. Thanks! -Jon & CLFU Team

Commands using echo from sorted by
Terminal - Commands using echo - 1,323 results
printf -v row "%${COLUMNS}s"; echo ${row// /#}
2010-04-13 21:56:46
User: dennisw
Functions: echo printf
Tags: tr tput printf

Pure Bash

This will print a row of characters the width of the screen without using any external executables. In some cases, COLUMNS may not be set. Here is an alternative that uses tput to generate a default if that's the case. And it still avoids using tr.

printf -v row "%${COLUMNS:-$(tput cols)}s"; echo ${row// /#}

The only disadvantage to either one is that they create a variable.

if cat /proc/cpuinfo | grep " lm " &> /dev/null; then echo "Got 64bit" ; fi
2010-04-10 15:31:58
User: xeor
Functions: cat echo grep
Tags: cpuinfo

Check if you have 64bit by looking for "lm" in cpuinfo. lm stands for "long mem". This can also be used without being root.

alias head='head -n $((${LINES:-`tput lines 2>/dev/null||echo -n 12`} - 2))'

Run the alias command, then issue

ps aux | head

and resize your terminal window (putty/console/hyperterm/xterm/etc) then issue the same command and you'll understand.

${LINES:-`tput lines 2>/dev/null||echo -n 12`}

Insructs the shell that if LINES is not set or null to use the output from `tput lines` ( ncurses based terminal access ) to get the number of lines in your terminal. But furthermore, in case that doesn't work either, it will default to using the deafault of 12 (-2 = 10).

The default for HEAD is to output the first 10 lines, this alias changes the default to output the first x lines instead, where x is the number of lines currently displayed on your terminal - 2. The -2 is there so that the top line displayed is the command you ran that used HEAD, ie the prompt.

Depending on whether your PS1 and/or PROMPT_COMMAND output more than 1 line (mine is 3) you will want to increase from -2. So with my prompt being the following, I need -7, or - 5 if I only want to display the commandline at the top. ( http://www.askapache.com/linux-unix/bash-power-prompt.html )


[7995:7993 - 0:186] 06:26:49 Thu Apr 08 [[email protected]:/dev/pts/0 +1] ~

In most shells the LINES variable is created automatically at login and updated when the terminal is resized (28 linux, 23/20 others for SIGWINCH) to contain the number of vertical lines that can fit in your terminal window. Because the alias doesn't hard-code the current LINES but relys on the $LINES variable, this is a dynamic alias that will always work on a tty device.

prefix="10.0.0" && for i in `seq 25`; do ping -c 1 $prefix.$i &> /dev/null && echo "Answer from: $prefix.$i" ; done
2010-04-07 17:17:21
User: xeor
Functions: echo ping
Tags: ping

Not really an easier solution. But an example using && for (if last command returned 0). You can use || for (if last command returned other than 0)..

for i in `find /home/ -maxdepth 1 -type d`; do echo -n $i " ";find $i|wc -l; done
2010-04-07 05:33:49
User: shantanuo
Functions: echo wc

Find the number of files from each folder

function ends_in_y() { case $(date +%A) in *y ) true ;; * ) false ;; esac } ; ends_in_y && echo ok
2010-04-06 22:18:52
Functions: date echo false true

The shell has perfectly adequate pattern matching for simple expressions.

function ends_in_y() { if [ `date +%A | sed -e 's/\(^.*\)\(.$\)/\2/'` == "y" ]; then echo 1; else echo 0; fi }
2010-04-06 20:14:34
User: allrightname
Functions: echo sed

For those days when you need to know if something is happening because the day ends in "y".

du -cks * | sort -rn | while read size fname; do for unit in k M G T P E Z Y; do if [ $size -lt 1024 ]; then echo -e "${size}${unit}\t${fname}"; break; fi; size=$((size/1024)); done; done
echo "scale=6;2048 / 2.345" | bc
echo Your_Chinese_Char | uniconv -encode Chinese-WB
2010-04-05 10:57:42
User: eastwind
Functions: echo

This CLI requiere the uniconv package that is provided with the yudit unicode editor .

The wubi86 is a way to type chinese far quicker than pinyin .

More infor on wikipedia : http://en.wikipedia.org/wiki/Wubizixing , http://www.yale.edu/chinesemac/wubi/xing.html

echo 'ServerAliveInterval 60' >> /etc/ssh/ssh_config
2010-03-31 09:22:54
User: rpavlick
Functions: echo
Tags: ssh timeout

ssh_config is the system-wide configuration file for ssh.

For per-user configuration, which allows for different settings for each host:

echo 'ServerAliveInterval 60' >> ~/.ssh/ssh_config


echo 'ServerAliveInterval 60' >> ~/.ssh/config


echo 'ServerAliveInterval 60' >> ~/etc/ssh_config
leapyear() { [ $(date -d "Dec 31, $1" +%j) == 366 ] && echo leap || echo not leap; }
leapyear() { if [ $[$1 % 4] -eq 0 ] && [ $[$1 % 100] -ne 0 ] || [ $[$1 % 400] -eq 0 ]; then echo $1' is a leap year!'; else echo $1' is not a leap year.'; fi; }
2010-03-30 17:19:20
User: kaedenn
Functions: echo
Tags: echo test

Tested on bash, and follows all the rules about leap years.

year=2010; math=`echo "$year%4" | bc`; [ ! -z $year ] && [ $math -eq 0 ] && echo "$year is leap year!" || echo "$year isn't leap year";
count="1" ; while true ; do read next ; if [[ "$next" = "$last" ]] ; then count=$(($count+1)) ; echo "$count" ; else count="1" ; echo $count ; fi ; last="$next" ; done
2010-03-30 04:02:29
User: dabom
Functions: echo read true
Tags: bash read Game

Really bored during class so I made this...

Basically, you hold period (or whatever) and hit enter after a second and you need to make the next line of periods the same length as the previous line...

My record was 5 lines of the same length.

It's best if you do it one handed with your pointer on period and ring on enter.

gorecord() { if [ $# != 1 ]; then echo 'gorecord video.mp4' return fi ffmpeg -f x11grab -s <resolution> -r 25 -i :0.0 -sameq -vcodec mpeg4 "$1" }
2010-03-29 20:21:35
User: meathive
Functions: echo return
gorecord foo.mp4

I've tried all of the screen recorders available for Linux and this is easily the best. xvidcap segfaults; VNC is too much hassle. There are alternatives of this command already here that I am just too lazy to reply to. Messing with the frames per second option, -r, 25 seems to be the best. Any lower and the video will look like a flipbook, if it records at all - -r 10 won't - any faster is the same, oddly enough.

Edit: CLF doesn't like my long command to add audio, so here it is in the description.

goaddaudio() { if [ $# != 3 ]; then echo 'goaddaudio < audio > < src video > < dst video >' return fi f=goaddaudio$RANDOM ffmpeg -i "$2" &> $f d=$( grep Duration $f | awk '{print $2}' | tr -d ',' ) && rm $f && ffmpeg -i "$1" -i "$2" -r 25 -ab 192k -ar 44100 -sameq -t $d "$3" }
ls -d $(echo ${PATH//:/ }) > /dev/null
for i in `seq 1 1 50`; do echo -n -; done
2010-03-25 10:22:19
User: Gosha
Functions: echo

This feels more intuitive to me.

OUTPUT="`find / -type f`" ; echo "$OUTPUT" | grep sysrq ; echo "$OUTPUT" | grep sysctl ; echo "$OUTPUT" | less
2010-03-25 05:02:10
Functions: echo grep sysctl

The example is a little bit bogus, but applies to any command that takes a while interactively, or might be a bit of a drag on system resources. Once the command's output is saved to a variable, you can then echo "$OUTPUT" to see it in multi-line glory after that. The use of double-quotes around the backticks and during the variable expansion disables any IFS conversion during those two operations.

Very useful for reporting that might pull different lines out, like from dmidecode, inq or any other disk detail command. The only caveat is that storing too much in a variable might make your shell process grow.

split -b4m file.tgz file.tgz. ; for i in file.tgz.*; do SUBJ="Backup Archive"; MSG="Archive File Attached"; echo $MSG | mutt -a $i -s $SUBJ YourEmail@(E)mail.com
2010-03-20 16:49:19
User: tboulay
Functions: echo split

This is just a little snippit to split a large file into smaller chunks (4mb in this example) and then send the chunks off to (e)mail for archival using mutt.

I usually encrypt the file before splitting it using openssl:

openssl des3 -salt -k <password> -in file.tgz -out file.tgz.des3

To restore, simply save attachments and rejoin them using:

cat file.tgz.* > output_name.tgz

and if encrypted, decrypt using:

openssl des3 -d -salt -k <password> -in file.tgz.des3 -out file.tgz

edit: (changed "g" to "e" for political correctness)

for i in be bg cz de es fi fr hu it lv lu at pl pt ro sk si ; do echo -n "$i " ; wget -q -O - http://www.expansys.$i/d.aspx?i=196165 | grep price | sed "s/.*<p id='price'><strong>&euro; \([0-9]*[,.][0-9]*\).*/\1/g"; done
2010-03-18 15:13:20
User: betsubetsu
Functions: at bg echo grep sed wget

You think Expansys in all these countries will sell the HTC Desire for the same price? Well, you'll be surprised. Most of them will be sold at 499.99 EUR but the cheapest can be found in Germany and the most expensive, in Belgium.

(echo "plot '-' with lines"; for x in $(seq 1 100); do curl -s "http://ajax.googleapis.com/ajax/services/search/web?v=1.0&q=$(echo $x bottles of beer on the wall|sed 's/ /%20/g')"|sed 's/.*"estimatedResultCount":"\([^"]*\)".*/\1\n/';done)|gnuplot -persist
2010-03-17 21:04:36
User: matthewbauer
Functions: echo sed seq

Will create a graph of the results for "x bottles of beer on the wall".

Requires Gnuplot.

Inspired by an xkcd comic: http://xkcd.com/715/

For sample output see: http://tr.im/xbottlesofbeer

echo $(( `ulimit -u` - `find /proc -maxdepth 1 \( -user $USER -o -group $GROUPNAME \) -type d|wc -l` ))
2010-03-12 08:42:49
User: AskApache
Functions: echo wc

There is a limit to how many processes you can run at the same time for each user, especially with web hosts. If the maximum # of processes for your user is 200, then the following sets OPTIMUM_P to 100.

OPTIMUM_P=$(( (`ulimit -u` - `find /proc -maxdepth 1 \( -user $USER -o -group $GROUPNAME \) -type d|wc -l`) / 2 ))

This is very useful in scripts because this is such a fast low-resource-intensive (compared to ps, who, lsof, etc) way to determine how many processes are currently running for whichever user. The number of currently running processes is subtracted from the high limit setup for the account (see limits.conf, pam, initscript).

An easy to understand example- this searches the current directory for shell scripts, and runs up to 100 'file' commands at the same time, greatly speeding up the command.

find . -type f | xargs -P $OPTIMUM_P -iFNAME file FNAME | sed -n '/shell script text/p'

I am using it in my http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html especially for the xargs command. Xargs has a -P option that lets you specify how many processes to run at the same time. For instance if you have 1000 urls in a text file and wanted to download all of them fast with curl, you could download 100 at a time (check ps output on a separate [pt]ty for proof) like this:

cat url-list.txt | xargs -I '{}' -P $OPTIMUM_P curl -O '{}'

I like to do things as fast as possible on my servers. I have several types of servers and hosting environments, some with very restrictive jail shells with 20processes limit, some with 200, some with 8000, so for the jailed shells my xargs -P10 would kill my shell or dump core. Using the above I can set the -P value dynamically, so xargs always works, like this.

cat url-list.txt | xargs -I '{}' -P $OPTIMUM_P curl -O '{}'

If you were building a process-killer (very common for cheap hosting) this would also be handy.

Note that if you are only allowed 20 or so processes, you should just use -P1 with xargs.

echo "ulimit `ulimit -a|sed -e 's/^.*\([a-z]\))\(.*\)$/-\1\2/'|tr "\n" ' '`"
2010-03-12 06:46:54
User: AskApache
Functions: echo

It is helpful to know the current limits placed on your account, and using this shortcut is a quick way to figuring out which values to change for optimization or security.

Alias is:

alias ulimith="command ulimit -a|sed 's/^.*\([a-z]\))\(.*\)$/-\1\2/;s/^/ulimit /'|tr '\n' ' ';echo"

Here's the result of this command:

ulimit -c 0 -d unlimited -e 0 -f unlimited -i 155648 -l 32 -m unlimited -n 8192 -p 8 -q 819200 -r 0 -s 10240 -t unlimited -u unlimited -v unlimited -x unlimited ulimit -a

core file size (blocks, -c) 0

data seg size (kbytes, -d) unlimited

scheduling priority (-e) 0

file size (blocks, -f) unlimited

pending signals (-i) 155648

max locked memory (kbytes, -l) 32

max memory size (kbytes, -m) unlimited

open files (-n) 8192

pipe size (512 bytes, -p) 8

POSIX message queues (bytes, -q) 819200

real-time priority (-r) 0

stack size (kbytes, -s) 10240

cpu time (seconds, -t) unlimited

max user processes (-u) unlimited

virtual memory (kbytes, -v) unlimited

file locks (-x) unlimited

function setTerm() { PROFILE=${1}; echo "tell app \"Terminal\" to set current settings of first window to settings set \"${PROFILE}\""|osascript; };