Commands by pamirian (5)

  • dname is a directory named something like 20090803 for Aug 3, 2009. lastbackup is a soft link to the last backup made - say 20090802. $folder is the folder being backed up. Because this uses hard linking, files that already exist and haven't changed take up almost no space yet each date directory has a kind of "snapshot" of that day's files. Naturally, lastbackup needs to be updated after this operation. I must say that I can't take credit for this gem; I picked it up from somewhere on the net so long ago I don't remember where from anymore. Ah, well... Systems that are only somewhat slicker than this costs hundreds or even thousands of dollars - but we're HACKERS! We don't need no steenkin' commercial software... :)


    6
    rsync -a --delete --link-dest=../lastbackup $folder $dname/
    pamirian · 2009-08-04 07:08:54 4
  • This requires the command-line print extension (see #2861 for more details). I use it to make up complex images with formatted text using CSS and whatnot. It's a lot slicker than imagemagick for certain things. Now imagine using a local webserver with PHP and a database to generate the images. Oh, the possibilities...


    9
    touch $2;firefox -print $1 -printmode PNG -printfile $2
    pamirian · 2009-08-04 06:55:25 1
  • This uses the "command-line print" plugin for Firefox (http://torisugari.googlepages.com/commandlineprint2). This same plugin can also produce PNGs. On *nix, the file must exist; therefore the touch bit in front. Also, firefox seems to ignore saved user preferences when "printing" this way (margins, header, footer, etc.), so I had to tweak my ~/.mozilla/firefox/xxxxxxxx.default/prefs.js file by hand. Yup, that's *prefs.js* not user.js - apparently, firefox ignores my user.js file too...


    5
    touch $2;firefox -print $1 -printmode PDF -printfile $2
    pamirian · 2009-08-04 06:40:55 0
  • This is an extract from a larger script which formats the video for DVD. The videos I use have no audio track so I need to add one. Tweak as you like...


    6
    cat frame/*.mpeg | ffmpeg -i $ID.mp3 -i - -f dvd -y track/$ID.mpg 2>/dev/null
    pamirian · 2009-08-04 06:31:50 0
  • This is an extract from a larger script which makes up slideshow videos from images. $seconds is the number of seconds the video will last, and $num is a loop counter which numbers the videos for concat into a longer video later, so they will be in order. The dev/null bit on the end cuts ffmpeg's verbosity.


    4
    ffmpeg -loop_input -f image2 -r 30000/1001 -t $seconds -i frame/$num.ppm -y frame/%02d.mpeg 2>/dev/null
    pamirian · 2009-08-04 06:25:47 0

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Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

Every Nth line position # (AWK)
A better way to show the file lines 3n + 1

Clean up display when the bash prompt is displayed
This will cause bash to fix a garbled terminal before the prompt is printed. For example, if you cat a file with nonprintable character sequences, the terminal sometimes ends up in a mode where it only prints line drawing characters. This sequence will return the terminal to the standard character set after every command.

Extracting frames from a video as jpeg files
This command extracts 10 seconds worth of frames, starting from 00:15:45 position, from filename.avi and stores them into out_frames folder as jpeg files. Subtitles are turned off with -sid 999 option.

Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

Show sorted list of files with sizes more than 1MB in the current dir

shell equivalent of a boss button
Nobody wants the boss to notice when you're slacking off. This will fill your shell with random data, parts of it highlighted. Note that 'highlight' is the Perl module App::highlight, not "a universal sourcecode to formatted text converter." You'll also need Term::ANSIColor.

Vim: Switch from Horizontal split to Vertical split
This allows to switch from horizontal to vertical split, putting the current buffer on the right side of the vertical split. To put it on the right use ^W-H. In a similar way, to switch from Vertical to Horizontal, do ^W-J (for bottom) and ^W-K (for top), but you vimers all guessed that one already :P

Mirror a directory structure from websites with an Apache-generated file indexes
wget/curl/friends are not good with mirroring files off websites, especially those with Apache-generated directory listings. These tools endlessly waste time downloading useless index HTML pages. lftp's mirror command does a better job without the mess.

Convert A USB Cable Into A Smart Home Gadget
An old USB A/B cable is all you need to make your own Smart Home hardware! Cut off and discard the B-portion of the USB cable. On the A side, connect the RED (+) and WHITE (D-) wires via a 1 kiloohm resistor. $Picture: http://imgur.com/dJGVlAU Now plug the cable into a USB port on your Linux computer. Your hardware is ready! Run the above command after changing variable mysms to your personal email-to-SMS gateway info as required by your cellular service provider. The command uses the amazing usbmon tool (see link below) to detect the cable. For the curious, to view the raw usbmon output, run this command: (Also see the sample output) $usbmon -i usb0 How does it work? When the red and white wires are connected (via the 1 kiloohm resistor) the USB hardwere is tricked into thinking that a new USB device is trying to start up. We then use the usbmon utility to capture the host USB events as it tries to talk to the cable. The expect utility watches the usbmon stream and waits for the disconnect text "-2:128" before sending the SMS message. Finally, the sendmail tool is used to email the SMS message to your smartphone via your cellular provider's SMS-to-email gateway. As a result, when the electrical connection between the red and white wire is interrupted, or the USB cable is unplugged from your computer, you get an SMS notification of the disconnect event on your smartphone. Could this be the cheapest smart home gadget ever? What are YOU going to sense with it? Please let me know in the comments and please don't forget to click it up! $ $Links: $ http://www.linuxcertif.com/man/8/usbmon/ http://en.wikipedia.org/wiki/USB#Pinouts http://imgur.com/dJGVlAU


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