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 24
  • 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 4
  • 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 7
  • 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 5
  • 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 4

  • 0
    find /logdir -type f -mtime +7 -print0 | xargs -0 -n 1 nice -n 20 bzip2 -9
    rootninja · 2014-02-12 19:35:09 6

  • -6
    nice -n0 ls | mpg321 -@- &
    kev · 2011-07-10 11:50:46 7

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Run a command only when load average is below a certain threshold
Good for one off jobs that you want to run at a quiet time. The default threshold is a load average of 0.8 but this can be set using atrun.

Convert spaces in file names to underscores

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

list folders containing less than 2 MB of data
This command will search all subfolders of the current directory and list the names of the folders which contain less than 2 MB of data. I use it to clean up my mp3 archive and to delete the found folders pipe the output to a textfile & run: $ while read -r line; do rm -Rv "$line"; done < textfile

Burn CD/DVD from an iso, eject disc when finished.
cdrecord -scanbus will tell you the (x,y,z) value of your cdr (for example, mine is 3,0,0)

Run a command for blocks of output of another command
The given example collects output of the tail command: Whenever a line is emitted, further lines are collected, until no more output comes for one second. This group of lines is then sent as notification to the user. You can test the example with $ logger "First group"; sleep 1; logger "Second"; logger "group"

ASCII art of yourself
Use libcaca to render ascii chars on the webcam input... or don't.

batch convert Nikon RAW (nef) images to JPG
converts RAW files from a Nikon DSLR to jpg for easy viewing etc. requires ufraw package

a function to create a box of '=' characters around a given string.
First argument: string to put a box around. Second argument: character to use for box (default is '=') Same as command #4948, but shorter, and without the utility function.

Backup all mysql databases to individual files on a remote server
It grabs all the database names granted for the $MYSQLUSER and gzip them to a remote host via SSH.


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