Commands by mungewell (4)

  • Convert numbers to SI notation

    converts any number on the 'stdin' to SI notation. My version limits to 3 digits of precious (working with 10% resistors). Show Sample Output


    2
    $ awk '{ split(sprintf("%1.3e", $1), b, "e"); p = substr("yzafpnum_kMGTPEZY", (b[2]/3)+9, 1); o = sprintf("%f", b[1] * (10 ^ (b[2]%3))); gsub(/\./, p, o); print substr( gensub(/_[[:digit:]]*/, "", "g", o), 1, 4); }' < test.dat
    mungewell · 2009-07-22 16:54:14 57
  • Efficiently extract lines between markers

    GNU Sed can 'address' between two regex, but it continues parsing through to the end of the file. This slight alteration causes it to terminate reading the input file once the STOP match is made. In my example I have included an extra '/START/d' as my 'start' marker line contains the 'stop' string (I'm extracting data between 'resets' and using the time stamp as the 'start'). My previous coding using grep is slightly faster near the end of the file, but overall (extracting all the reset cycles in turn) the new SED method is quicker and a lot neater. Show Sample Output


    3
    sed -n '/START/,${/STOP/q;p}'
    mungewell · 2009-06-19 15:27:36 12
  • Apply substitution only on the line following a marker

    I've been auto-generating some complex GnuPlots; with multiplots the first plot of each group needs to be a 'plot' whereas the others need to be 'replots' to allow overplotting/autoscaling/etc to work properly. This is used to replace only the first instance of 'replot'. Show Sample Output


    5
    sed '/MARKER/{N;s/THIS/THAT/}'
    mungewell · 2009-06-12 02:29:50 4
  • Awk: Perform a rolling average on a column of data

    Sometimes jittery data hides trends, performing a rolling average can give a clearer view.


    3
    awk 'BEGIN{size=5} {mod=NR%size; if(NR<=size){count++}else{sum-=array[mod]};sum+=$1;array[mod]=$1;print sum/count}' file.dat
    mungewell · 2009-05-29 00:07:24 4

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

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Edit a file on a remote host using vim

Save your open windows to a file so they can be opened after you restart
This will save your open windows to a file (~/.windows). To start those applications: $ cat ~/.windows | while read line; do $line &; done Should work on any EWMH/NetWM compatible X Window Manager. If you use DWM or another Window Manager not using EWMH or NetWM try this: $ xwininfo -root -children | grep '^ ' | grep -v children | grep -v '' | sed -n 's/^ *\(0x[0-9a-f]*\) .*/\1/p' | uniq | while read line; do xprop -id $line _NET_WM_PID | sed -n 's/.* = \([0-9]*\)$/\1/p'; done | uniq -u | grep -v '^$' | while read line; do ps -o cmd= $line; done > ~/.windows

Escape forward slashes in a variable
For example $ path="/etc/apt/sources.list"; echo ${path//'/'/'\/'} will print $ \/etc\/apt\/sources.list

highlight with grep and still output file contents

list block devices
Shows all block devices in a tree with descruptions of what they are.

remove OSX resource forks ._ files
DESCRIPTION For each dir, dot_clean recursively merges all ._* files with their cor- responding native files according to the rules specified with the given arguments. By default, if there is an attribute on the native file that is also present in the ._ file, the most recent attribute will be used. If no operands are given, a usage message is output. If more than one directory is given, directories are merged in the order in which they are specified.

Separates each frame of a animated gif file to a counted file, then appends the frames together into one sheet file. Useful for making sprite sheets for games.
requires imagemagick

Redirect tar extract to another directory
The command extracting the tar contents into particular directory ...

Have subversion ignore a file pattern in a directory
If you don't want to commit files to subversion, and don't want those file to show up when doing an "svn stat", this command is what you need

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: