Commands by ppq (2)

  • If, for example, you want to remove all kernels and headers but the last three versions, you can't use one of that magic all-in-one "remove old stuff" commands. With this simple but elegant command you can remove a range of versions, or a list of versions with e.g. {14,16,20}. Show Sample Output

    apt purge linux*{14..18}*
    ppq · 2016-04-20 07:44:55 0
  • This is the fastest way to burn a DVD-Video from the command line. Dependencies: libav-tools dvdauthor growisofs The first command: avconv -i input.avi -target pal-dvd dvd.mpg converts any given video file avconv can handle into MPEG2-PS (6 Mbit/s) with AC3 audio (448 kbit/s). If your distribution is not up to date, just use ffmpeg - the syntax is the same. Hint: If you want to create an NTSC DVD, type ntsc-dvd instead ;-) The second command: echo PAL > ~/.config/video_format sets PAL as your default video format. This is a workaround for an old dvdauthor bug. If you want NTSC, guess what? Type NTSC instead! The third command: dvdauthor -o dvd/ -t dvd.mpg creates .VOB files and adds them to the dvd/ folder. You don't have to create this folder yourself. You can add as many titles as you like, just keep in mind that there's a maximum of 4482 MiB (4.37 GiB) for normal DVDs. The fourth command: dvdauthor -o dvd/ -T finishes the DVD-Video. Now you can burn your DVD using growisofs: growisofs -Z /dev/dvd -dvd-video dvd/ Sources: manpages

    avconv -i input.avi -target pal-dvd dvd.mpg && echo PAL > ~/.config/video_format && dvdauthor -o dvd/ -t dvd.mpg && dvdauthor -o dvd/ -T && growisofs -Z /dev/dvd -dvd-video dvd/
    ppq · 2012-09-09 20:56:54 0

What's this? 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

Cropping a video file in ffmpeg

One command line web server on port 80 using nc (netcat)
Very simple web server listening on port 80 will serve index.html file or whatever file you like pointing your browser at http://your-IP-address/index.html for example. If your web server is down for maintenance and you'd like to inform your visitors about it, quickly and easily, you just have to put into the index.html file the right HTML code and you are done! Of course you need to be root to run the command using port 80.

Open screen on the previous command
I often find myself wanting to open screen on whatever command I'm currently running. Unfortunately, opening a fresh screen session spawns a new bash session, which doesn't keep my history, so calling screen directly with the previous command is the only way to go.

Print a row of characters across the terminal
Print a row of characters across the terminal. Uses tput to establish the current terminal width, and generates a line of characters just long enough to cross it. In the example '#' is used. It's possible to use a repeating sequence by dividing the columns by the number of characters in the sequence like this: $ seq -s'~-' 0 $(( $(tput cols) /2 )) | tr -d '[:digit:]' or $ seq -s'-~?' 0 $(( $(tput cols) /3 )) | tr -d '[:digit:]' You will lose chararacters at the end if the length isn't cleanly divisible.

Join lines
It's works only when you replace '\n' to ONE character.

SAR - List the average memory usage for all days recorded under '/var/log/sa/*' using sar -r.

view the system console remotely
This will view the console and assumes the screen is 80 characters wide. Use /dev/vcs2 for the next virtual console.. etc.

Don't save commands in bash history (only for current session)
Only from a remote machine: Only access to the server will be logged, but not the command. The same way, you can run any command without loggin it to history. ssh user@localhost will be registered in the history as well, and it's not usable.

Copy one file to multiple files
Copies to file.copy1 ... file.copyn

DVD ripping with ffmpeg
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.

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.


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: