Commands using nice (7)

  • To rip DVD movie to ogg format using ffmpeg, follow these steps. 1) find the vob files on the mounted video DVD in VIDEO_TS that stores the movie itself. There would be a few other VOB files that stores splash screen or special features, the vob files for the movie itself can be identified by its superior size. You can verify these vob files by playing them directly with a player (e.g. mplayer) 2) concatenate all such vob files, pipe to ffmpeg 3) calculate the video size and crop size. The ogg video size must be multiple of 16 on both width and height, this is inherit limitation of theora codec. In my case I took 512x384. The -vcodec parameter is necessary because ffmpeg doesn't support theora by itself. -acodec is necessary otherwise ffmpeg uses flac by default.


    5
    cat VIDEO_TS/VTS_01_[1234].VOB | nice ffmpeg -i - -s 512x384 -vcodec libtheora -acodec libvorbis ~/Videos/dvd_rip.ogg
    zhangweiwu · 2010-09-14 14:45:27 22
  • This takes the stream created by apache requests containing jsp and funnels them to another server. I'm using this for simulating real time traffic. The nice command gives ssh maximum CPU cycles, awk & grep strip out everything served by apache. Putting parallel on curl is important because curl is synchronous and waits for the response. Yes, I thought about using wget but it didn't seem any easier. Also, if you figure out how to run this in the background let me know. Every time I background it it stops. If you have multiple front end servers just run multiple instances of this.


    3
    nice -n -20 ssh SOURCE_SERVER "tail -f /var/log/httpd/access.log " | awk '{print $7}' | grep jsp | parallel 'curl TARGET_SERVER{} 2>&1 /dev/null'
    dennisfaust · 2011-05-09 19:32:40 3
  • Check out the usage of 'trap', you may not have seen this one much. This command provides a way to schedule commands at certain times by running them after sleep finishes sleeping. In the example 'sleep 2h' sleeps for 2 hours. What is cool about this command is that it uses the 'trap' builtin bash command to remove the SIGHUP trap that normally exits all processes started by the shell upon logout. The 'trap 1' command then restores the normal SIGHUP behaviour. It also uses the 'nice -n 19' command which causes the sleep process to be run with minimal CPU. Further, it runs all the commands within the 2nd parentheses in the background. This is sweet cuz you can fire off as many of these as you want. Very helpful for shell scripts.


    2
    ( trap '' 1; ( nice -n 19 sleep 2h && command rm -v -rf /garbage/ &>/dev/null && trap 1 ) & )
    AskApache · 2009-10-10 04:43:44 6
  • This command will nicely dump a filesystem to STDOUT, compress it, encrypt it with the gpg key of your choice, throttle the the data stream to 60kb/s and finally use ssh to copy the contents to an image on a remote machine. Show Sample Output


    2
    nice -n19 dump -0af - /<filesystem> -z9|gpg -e -r <gpg key id>|cstream -v 1 -t 60k|ssh <user@host> "cat > backup.img"
    din7 · 2009-10-29 18:27:25 4
  • This is a simple command which makes electricsheep render directly to your background


    0
    nice -n 5 electricsheep -window-id `xwininfo -root|head -n 2|grep xwininfo|cut -c 22-26`
    kbaegis · 2011-02-14 03:58:58 1

  • 0
    find /logdir -type f -mtime +7 -print0 | xargs -0 -n 1 nice -n 20 bzip2 -9
    rootninja · 2014-02-12 19:35:09 3

  • -6
    nice -n0 ls | mpg321 -@- &
    kev · 2011-07-10 11:50:46 6

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

encode HTML entities
Encodes HTML entities from input (file or stdin) so it's possible to directly past the result to a blog or HTML source file.

Search through files, ignoring .svn
By putting the "-not \( -name .svn -prune \)" in the very front of the "find" command, you eliminate the .svn directories in your find command itself. No need to grep them out. You can even create an alias for this command: $ alias svn_find="find . -not \( -name .svn -prune \)" Now you can do things like $ svn_find -mtime -3

Find broken symlinks and delete them
If you don't want to delete them, but just want to list them, do $ find -L /path -type l If you want to delete them with confirmation first, do $ find -L /path -type l -exec rm -i {} + Using the -L flag follows symlinks, so the -type l test only returns true if the link can't be followed, or is a symlink to another broken symlink.

Check reverse DNS
The +short option should make dig less chatty.

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

extract element of xml

Search commandlinefu from the command line
There's probably a more efficient way to do this rather than the relatively long perl program, but perl is my hammer, so text processing looks like a nail. This is of course a lot to type all at once. You can make it better by putting this somewhere: $ clf () { (curl -d "q=$@" http://www.commandlinefu.com/search/autocomplete 2>/dev/null) | egrep 'autocomplete|votes|destination' | perl -pi -e 's/$/\n\n/g;s/^ +|\([0-9]+ votes,//g;s/^\//http:\/\/commandlinefu.com\//g'; } Then, to look up any command, you can do this: $ clf diff This is similar to http://www.colivre.coop.br/Aurium/CLFUSearch except that it's just one line, so more in the spirit of CLF, in my opinion.

Replace Every occurrence of a word in a file
Replace 'this' with 'that'

Want to known what time is it in another part of the world ?
available timezone can be found in /usr/share/zoneinfo. Other examples: $ TZ=Europe/Paris date; TZ=Australia/Sydney date; TZ=America/New_York date this is based on zoneinfo files on macosx. Your mileage my vary on other unix dialects

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


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: