Commands by adamhotep (4)

  • This will take the packages matching a given `apt-cache search` query (a collection of AND'd words or regexps) and tell you how popular they are. This is particularly nice for those times you have to figure out which solution to use for e.g. a PDF reader or a VNC client. Substitute "ubuntu.com" for "debian.org" if you want this to use Ubuntu's data instead. Everything else will work perfectly. Show Sample Output


    4
    apt-popcon() { (echo \#rank; apt-cache search "$@" |awk '$1 !~ /^lib/ {print " "$1" "}') |grep -Ff- <(wget -qqO- http://popcon.debian.org/by_inst.gz |gunzip); }
    adamhotep · 2012-09-08 00:29:31 0
  • This is like `cd -` but doesn't echo the new directory name, which is preferable (to me) for an alias, e.g. alias cdo="cd $OLDPWD"


    -2
    cd $OLDPWD
    adamhotep · 2012-04-16 21:18:27 0
  • shorter version. I believe find is faster than ls as well.


    0
    find . -type d |sed 's:[^-][^/]*/:--:g; s:^-: |:'
    adamhotep · 2012-04-14 00:51:09 2
  • A tweak using Patola's code as a base, this full-width green matrix display has all the frills (and all the printable characters). You don't need the surrounding parens if you don't care about losing globbing capabilities. Z-shell (/bin/zsh) needs neither the parens nor the `set -o noglob` Screen shot (animated): http://desmond.imageshack.us/Himg32/scaled.php?server=32&filename=matrixh.gif&res=landing If it's too slow, try lowering the `sleep 0.05` or even replacing it with `true` (which is faster than `sleep 0`). I squashed it as narrow as I could to conserve space, though somebody could probably squeeze a char or two out. Enjoy!


    0
    (set -o noglob;while sleep 0.05;do for r in `grep -ao '[[:print:]]' /dev/urandom|head -$((COLUMNS/3))`;do [ $((RANDOM%6)) -le 1 ] && r=\ ;echo -ne "\e[$((RANDOM%7/-6+2));32m $r ";done;echo;done)
    adamhotep · 2012-04-13 02:09:10 0

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

Benchmark SQL Query
Benchmark a SQL query against MySQL Server. The example runs the query 10 times, and you get the average runtime in the output. To ensure that the query does not get cached, use `RESET QUERY CACHE;` on top in the query file.

Recompress all text files in a subdirectory with lzma
This will deal nicely with filenames containing newlines and will run one lzma process per CPU core. It requires GNU Parallel http://www.youtube.com/watch?v=OpaiGYxkSuQ

save date and time for each command in history
Date-time format: YYYY-MM-DD HH:MM:SS

run a command from within vi without exiting
":! ls -l " results in listing the files in the current directory. pressing "enter" will get you back into vi.

Base conversions with bc
Easily convert numbers to their representations in different bases. Passing "ibase=16; obase=8; F2A" to bc will convert F2A (3882 in decimal) from Hex to Octal, and so on.

Using numsum to sum a column of numbers.
numsum is part of of the num-utils package, which is available in some Linux distros and can also be downloaded at http://suso.suso.org/xulu/Num-utils. It contains about 10 different programs for dealing with numbers from the command line. Obviously you can do a lot of things that the num-utils programs do in awk, sed, bash, perl scripts, but num-utils are there so that you don't have to remember the syntax for more complex operations and can just think: compute the sum, average, boundary numbers, etc.

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

Redirect incoming traffic to SSH, from a port of your choosing
Stuck behind a restrictive firewall at work, but really jonesing to putty home to your linux box for some colossal cave? Goodness knows I was...but the firewall at work blocked all outbound connections except for ports 80 and 443. (Those were wide open for outbound connections.) So now I putty over port 443 and have my linux box redirect it to port 22 (the SSH port) before it routes it internally. So, my specific command would be: $iptables -t nat -A PREROUTING -p tcp --dport 443 -j REDIRECT --to-ports 22 Note that I use -A to append this command to the end of the chain. You could replace that with -I to insert it at the beginning (or at a specific rulenum). My linux box is running slackware, with a kernel from circa 2001. Hopefully the mechanics of iptables haven't changed since then. The command is untested under any other distros or less outdated kernels. Of course, the command should be easy enough to adapt to whatever service on your linux box you're trying to reach by changing the numbers (and possibly changing tcp to udp, or whatever). Between putty and psftp, however, I'm good to go for hours of time-killing.

modify a file in place with perl
changes THIS to THAT in all files matching fileglob* without using secondary files

vi show line numbers
you don't have to spell out numbers, you can just use nu


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: