Commands using printf (206)

  • Convert number of bytes to human readable filesize

    Converts a number of bytes provided as input, to a human readable number. Show Sample Output


    2
    human_filesize() { awk -v sum="$1" ' BEGIN {hum[1024^3]="Gb"; hum[1024^2]="Mb"; hum[1024]="Kb"; for (x=1024^3; x>=1024; x/=1024) { if (sum>=x) { printf "%.2f %s\n",sum/x,hum[x]; break; } } if (sum<1024) print "1kb"; } '}
    ArtBIT · 2011-12-02 18:21:20 3
  • Matrix Style

    Unlike other alternatives, this command only relies on bash builtins and should also work on windows platforms with the bash executable. Sparseness corresponds to the number 128 and can be adjusted. To print all possible digits instead of only 0 and 1 replace RANDOM%2 by RANDOM%10 or RANDOM%16 to add letters [A-F]. Show Sample Output


    2
    while true; do printf "\e[32m%X\e[0m" $((RANDOM%2)); for ((i=0; i<$((RANDOM%128)); i++)) do printf " "; done; done
    seb1245 · 2012-11-27 10:40:42 11
  • Print today's date in ISO format without calling an external command (bash 4)


    2
    today() { printf '%(%Y-%m-%d)T\n' -1; } ## bash-4
    cfajohnson · 2013-01-27 06:17:25 6
  • urlencoding with one pure BASH builtin

    opposite of https://www.commandlinefu.com/commands/view/10014/urldecoding-with-one-pure-bash-builtin ;-) Show Sample Output


    2
    function URLEncode { local dataLength="${#1}"; local index; for ((index = 0;index < dataLength;index++)); do local char="${1:index:1}"; case $char in [a-zA-Z0-9.~_-]) printf "$char"; ;; *) printf "%%%02X" "'$char"; ;; esac; done; }
    emphazer · 2018-09-14 12:08:10 356
  • draw line separator (using knoppix5 idea)


    2
    printf '*%.s' {1..40}; echo
    metropolis · 2019-07-01 07:41:18 48
  • seconds since epoch to ISO timestamp

    No need to use perl, awk, nor /usr/bin/date -- bash's "printf" builtin will do it. Show Sample Output


    2
    printf '%(%FT%T)T\n' 1606752450
    Mozai · 2021-06-20 05:11:20 176
  • Big (four-byte) $RANDOM

    Sometimes, in a shell script, you need a random number bigger than the range of $RANDOM. This will print a random number made of four hex values extracted from /dev/urandom. Show Sample Output


    1
    printf %d 0x`dd if=/dev/urandom bs=1 count=4 2>/dev/null | od -x | awk 'NR==1 {print $2$3}'`
    introp · 2009-02-18 16:23:09 6
  • Doing some floating point calculations with rounding (e.g. at the 3rd decimal)


    1
    echo '123/7' |bc -l |xargs printf "%.3f\n"
    mrttlemonde · 2009-03-18 14:20:32 5
  • get the ascii number with bash builtin printf


    1
    printf "%d\n" "'A" "'B"
    twfcc · 2009-10-17 09:50:44 4
  • Get decimal ascii code from character

    printf treats first char after single ' as numeric equivalent


    1
    ord() { printf "%d\n" "'$1"; }
    zude · 2009-10-17 22:02:52 3
  • Find all dot files and directories


    1
    printf "%s\n" .*
    cfajohnson · 2009-11-20 21:41:02 3
  • Configuring proxy client on terminal without leaving password on screen or in bash_history

    Prompts the user for username and password, that are then exported to http_proxy for use by wget, yum etc Default user, webproxy and port are used. Using this script prevent the cleartext user and pass being in your bash_history and on-screen Show Sample Output


    1
    set-proxy () { P=webproxy:1234; DU="fred"; read -p "username[$DU]:" USER; printf "%b"; UN=${USER:-$DU}; read -s -p "password:" PASS; printf "%b" "\n"; export http_proxy="http://${UN}:${PASS}@$P/"; export ftp_proxy="http://${UN}:${PASS}@$P/"; }
    shadycraig · 2010-02-04 13:12:59 5
  • Url Encode

    This one uses hex conversion to do the converting and is in shell/sed only (should probably still use the python/perl version).


    1
    uri_escape(){ echo -E "$@" | sed 's/\\/\\\\/g;s/./&\n/g' | while read -r i; do echo $i | grep -q '[a-zA-Z0-9/.:?&=]' && echo -n "$i" || printf %%%x \'"$i" done }
    infinull · 2010-02-13 01:39:51 41
  • shell function to underline a given string.

    underline() will print $1, followed by a series of '=' characters the width of $1. An optional second argument can be used to replace '=' with a given character. This function is useful for breaking lots of data emitted in a for loop into sections which are easier to parse visually. Let's say that 'xxxx' is a very common pattern occurring in a group of CSV files. You could run grep xxxx *.csv This would print the name of each csv file before each matching line, but the output would be hard to parse visually. for i in *.csv; do printf "\n"; underline $i; grep "xxxx" $i; done Will break the output into sections separated by the name of the file, underlined. Show Sample Output


    1
    underline() { echo $1; for (( i=0; $i<${#1}; i=$i+1)); do printf "${2:-=}"; done; printf "\n"; }
    bartonski · 2010-02-26 05:46:49 8
  • a function to create a box of '=' characters around a given string.

    The function 'box' takes either one or two arguments. The first argument is a line of text to be boxed, the second argument (optional) is a character to use to draw the box. By default, the drawing character will be '='. The function 'n()' is a helper function used to draw the upper and lower lines of the box, its arguments are a length, and an character to print. (I used 'n' because 'line', 'ln' and 'l' are all commonly used) Show Sample Output


    1
    box() { l=${#1}+4;x=${2:-=};n $l $x; echo "$x $1 $x"; n $l $x; }; n() { for (( i=0; $i<$1; i=$i+1)); do printf $2; done; printf "\n"; }
    bartonski · 2010-02-26 06:56:59 3
  • Get acurate memory usage of a Process in MegaBytes


    1
    pmap $(pgrep [ProcessName] -n) | gawk '/total/ { a=strtonum($2); b=int(a/1024); printf b};'
    lv4tech · 2010-04-28 08:16:28 3
  • Combines an arbitrary number of transparent png files into one file

    This one liner; combines all sequentially numbered files; in this example IMG_0001.png to IMG_1121.png by generating the shell script, making the shell script executable and then running the shell script to combine the 1121 png into a single png file named _final.png tested on Mac OS X 10.6.3 with ImageMagick 6.5.8-0 2009-11-22 Q16 http://www.imagemagick.org


    1
    echo -n "convert " > itcombino.sh; printf "IMG_%00004u.png " {1..1121} >> itcombino.sh; echo -n "-layers merge _final.png" >> itcombino.sh; chmod +x itcombino.sh && ./itcombino.sh
    IsraelTorres · 2010-05-22 03:56:30 5
  • create a new script, automatically populating the shebang line, editing the script, and making it executable.

    The first argument is the interpreter for your script, the second argument is the name of the script to create. Show Sample Output


    1
    shebang() { if i=$(which $1); then printf '#!%s\n\n' $i > $2 && vim + $2 && chmod 755 $2; else echo "'which' could not find $1, is it in your \$PATH?"; fi; }
    bartonski · 2011-03-09 14:47:32 25
  • Watch RX/TX rate of an interface in kb/s

    A shorter version Show Sample Output


    1
    while cat /proc/net/dev; do sleep 1; done | awk '/eth0/ {o1=n1; o2=n2; n1=$2; n2=$10; printf "in: %9.2f\t\tout: %9.2f\r", (n1-o1)/1024, (n2-o2)/1024}'
    quadcore · 2011-03-26 02:52:14 3
  • monitor your CPU core temperatures in real time

    Watch the temperatures of your CPU cores in real time at the command line. Press CONTROL+C to end. GORY DETAILS: Your computer needs to support sensors (many laptops, for example, do not). You'll need to install the lm-sensors package if it isn't already installed. And it helps to run the `sensors-detect` command to set up your sensor kernel modules first. At the very end of the sensors-detect interactive shell prompt, answer YES to add the new lines to the list of kernel modules loaded at boot. Show Sample Output


    1
    while :; do sensors|grep ^Core|while read x; do printf '% .23s\n' "$x"; done; sleep 1 && clear; done;
    linuxrawkstar · 2011-04-20 06:41:57 7
  • Colored status of running services

    Replace service --status-all 2>&1 by service --status-all 2>/dev/null to hide all services with the status [ ? ]


    1
    services() { printf "$(service --status-all 2>&1|sed -e 's/\[ + \]/\\E\[42m\[ + \]\\E\[0m/g' -e 's/\[ - \]/\\E\[41m\[ - \]\\E\[0m/g' -e 's/\[ ? \]/\\E\[43m\[ ? \]\\E\[0m/g')\n";}
    stanix · 2011-04-23 12:38:09 4
  • Scan for [samba|lanman] NetBIOS names and ip addresses in LAN by ARP.


    1
    arp-scan -I eth0 -l | perl -ne '/((\d{1,3}\.){3}\d{1,3})/ and $ip=$1 and $_=`nmblookup -A $ip` and /([[:alnum:]-]+)\s+<00>[^<]+<ACTIVE>/m and printf "%15s %s\n",$ip,$1'
    bandie91 · 2011-07-08 07:41:41 3
  • Generate a shortened URL with is.gd

    Check the API. You shouldn't need sed. The print-newline at the end is to prevent zsh from inserting a % after the end-of-output. Also works with http://v.gd Show Sample Output


    1
    isgd () { curl 'http://is.gd/create.php?format=simple&url='"$1" ; printf "\n" }
    dbbolton · 2011-08-14 23:31:39 3
  • One line Perl Script to determine the largest file sizes on a Linux Server

    This one line Perl script will display the smallest to the largest files sizes in all directories on a server. Show Sample Output


    1
    du -k | sort -n | perl -ne 'if ( /^(\d+)\s+(.*$)/){$l=log($1+.1);$m=int($l/log(1024)); printf ("%6.1f\t%s\t%25s %s\n",($1/(2**(10*$m))),(("K","M","G","T","P")[$m]),"*"x (1.5*$l),$2);}' | more
    Q_Element · 2012-02-07 15:49:19 10
  • Count all files in directories recursively with find

    Counts the files present in the different directories recursively. One only has to change maxdepth to have further insight in the directory hierarchy. Found at unix.stackexchange.com: http://unix.stackexchange.com/questions/4105/how-do-i-count-all-the-files-recursively-through-directories Show Sample Output


    1
    find -maxdepth 3 -type d | while read -r dir; do printf "%s:\t" "$dir"; find "$dir" | wc -l; done
    brainstorm · 2012-10-15 15:00:09 7
  • ‹ First  < 2 3 4 5 6 >  Last ›

What's this?

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

Share Your Commands

Check These Out

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

seq (argc=2) for FreeBSD

Get a list of IP Addresses that have failed to login via SSH
This command shows a sorted list of the IP addresses from which there have been authentication errors via SSH (possible script kiddies trying to gain access to your server), it eliminates duplicates so it's easier to read, but you can remove the "uniq" command at the end, or even do a "uniq -c" to have a count of how many times each IP address shows in the log (the path to the log may vary from system to system)

RTFM function
Same as the other rtfm's, but using the more correct xdg-open instead of $BROWSER. I can't find a way to open info only if the term exists, so it stays out of my version.

Play radio stream with mplayer
Above command will play Virgin Radio Dubai

display a smiling smiley if the command succeeded and a sad smiley if the command failed
you could save the code between if and fi to a shell script named smiley.sh with the first argument as and then do a smiley.sh to see if the command succeeded. a bit needless but who cares ;)

Extracts PDF pages as images

Make a DVD ISO Image from a VIDEO_TS folder on MacOSX
/path/ is the root folder of the DVD, not the VIDEO_TS folder.

View advanced Sort options, Quick Reference Help Alias
Once you get into advanced/optimized scripts, functions, or cli usage, you will use the sort command alot. The options are difficult to master/memorize however, and when you use sort commands as much as I do (some examples below), it's useful to have the help available with a simple alias. I love this alias as I never seem to remember all the options for sort, and I use sort like crazy (much better than uniq for example). # Sorts by file permissions $ find . -maxdepth 1 -printf '%.5m %10M %p\n' | sort -k1 -r -g -bS 20% 00761 drwxrw---x ./tmp 00755 drwxr-xr-x . 00701 drwx-----x ./askapache-m 00644 -rw-r--r-- ./.htaccess # Shows uniq history fast $ history 1000 | sed 's/^[0-9 ]*//' | sort -fubdS 50% exec bash -lxv export TERM=putty-256color Taken from my http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

Key binding to search commandlinefu.com
This is a simple bash function and a key binding that uses commandlinefu's simple and easy search API. It prompts for a search term, then it uses curl to search commandline fu, and highlights the search results with less.

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: