Commands tagged array (8)

  • If you should happen to find yourself needing some binary numbers, this is a quickie way of doing it. If you need more digits, just add more "{0..1}" sequences for each digit you need. You can assign them to an array, too, and access them by their decimal equivalent for a quickie binary to decimal conversion (for larger values it's probably better to use another method). Note: this works in bash, ksh and zsh. For zsh, though, you'll need to issue a setopt KSH_ARRAYS to make the array zero-based. binary=({0..1}{0..1}{0..1}{0..1}) echo ${binary[9]} Show Sample Output


    18
    echo {0..1}{0..1}{0..1}{0..1}
    dennisw · 2009-06-23 17:30:20 11

  • 10
    read -a ARR <<<'world domination now!'; echo ${ARR[2]};
    unefunge · 2010-12-03 16:27:03 6
  • Convert some decimal numbers to binary numbers. You could also build a general base-converter: function convBase { echo "ibase=$1; obase=$2; $3" | bc; } then you could write function decToBun { convBase 10 2 $1; } Show Sample Output


    4
    function decToBin { echo "ibase=10; obase=2; $1" | bc; }
    woxidu · 2009-11-24 22:57:58 4
  • Like 7171, but fixed typo, uses fewer variables, and even more cryptic! Show Sample Output


    4
    read -a A<<<".*.**..*....*** 8 9 5 10 6 0 2 11 7 4";for C in `date +"%H%M"|fold -w1`;do echo "${A:${A[C+1]}:4}";done
    __ · 2010-12-02 22:04:49 5
  • This type of join is clearly documented in the bash manual. Only the first character of IFS is used for the delimiter. Show Sample Output


    4
    (IFS=,; echo "${array[*]}")
    aspiers · 2013-09-25 10:36:38 11
  • cryptic version Show Sample Output


    2
    read -a A <<<"8 9 5 10 6 0 3 11 7 4";B='.*.**..*....***';for C in $(date +"%H%M"|fold -w1);do echo "${B:${A[C]}:4}";done
    unefunge · 2010-11-26 11:29:23 6
  • I was looking for the fastest way to create a bunch of ansi escapes for use in echo -e commands throughout a lot of my shell scripts. This is what I came up with, and I actually stick that loop command in a function and then just call that at the beginning of my scripts to not clutter the environment with these escape codes, which can wreck havok on my terminal when I'm dumping the environment. More of a cool way to store escape ansi codes in an array. You can echo them like: echo -e "${CC[15]}This text is black on bright green background." I usually just use with a function: # setup_colors - Adds colors to array CC for global use # 30 - Black, 31 - Red, 32 - Green, 33 - Yellow, 34 - Blue, 35 - Magenta, 36 - Blue/Green, 37 - White, 30/42 - Black on Green '30\;42' function setup_colors(){ declare -ax CC; for i in `seq 0 7`;do ii=$(($i+7));CC[$i]="\033[1;3${i}m";CC[$ii]="\033[0;3${i}m";done;CC[15]="\033[30;42m"; export R='\033[0;00m';export X="\033[1;37m"; }; export -f setup_colors CC[15] has a background of bright green which is why it is separate. R resets everything, and X is my default font of bright white. CC[15]="\033[30;42m"; R=$'\033[0;00m'; X=$'\033[1;37m' Those are just my favorite colors that I often use in my scripts. You can test which colors by running for i in $(seq 0 $((${#CC[@]} - 1))); do echo -e "${CC[$i]}[$i]\n$R"; done See: http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html for more usage. Show Sample Output


    1
    declare -ax CC; for i in `seq 0 7`;do ii=$(($i+7)); CC[$i]="\033[1;3${i}m"; CC[$ii]="\033[0;3${i}m"; done
    AskApache · 2009-09-21 07:00:55 8
  • 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! Show Sample Output


    0
    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"";}
    bbbco · 2012-01-20 21:18:16 5

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

Uniquely (sort of) color text so you can see changes
Colorify colors input by converting the text to a number and then performing modulo 7 on it. This resulting number is used as the color escape code. This can be used to color the results of commands with complex outputs (like "482279054165371") so if any of the digits change, there's a good chance the color will change too. I say good chance because there's only 7 unique colors here, so assuming you were watching random numbers, there would be a 6/7 chance that the color would change when the number changed. This should really only be used to help quickly identify when things change, but should not be the only thing relied upon to positively assert that an output has not changed.

Leap year calculation

convert ascii string to hex
Even adds a newline.

Rename files in batch

Erase to factory a pendrive, disk or memory card, and watch the progress

Find the package that installed a command

Remove a line in a text file. Useful to fix
In this case it's better do to use the dedicated tool

Execute a command at a given time
This is an alternative to cron which allows a one-off task to be scheduled for a certain time.

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Hide or show Desktop Icons on MacOS
Hides all Files and Folders on the MacOS Desktop. To show files and folders, type "true" instead of "false". "Finder" at the end is case sensitive, "finder" doesn’t work


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: