Ubuntu Commands for some useful tasks
Below some useful commands for carrying out tasks in ubuntu via the terminal are mentioned :-
- Resize image
- Resize pdf
- Download mp3 audio from a Youtube video
- Convert any video file to lossless "flac" audio format
- Convert any video file to "mp3" audio format
- Resize image :
convert -resize 50% -quality 99 IMG_20160623_203259.jpg output.jpg
convert is in package imagemagick
===============
- Resize pdf :
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf
If the -dPDFSETTINGS=/screen setting is too low quality to suit your needs, replace it with -dPDFSETTINGS=/ebook for better quality, but slightly larger pdfs. Delete the setting altogether for the high quality default, which you can also explicitly call for with -dPDFSETTINGS=/prepress.
source : http://askubuntu.com/questions/113544/how-can-i-reduce-the-file-size-of-a-scanned-pdf-file
Alternate : pdfsam ( The version in ubuntu respository is old , latest version at http://www.pdfsam.org/downloads/ )
============
- Rotate pdf :
sudo apt-get install pdftk (22 MB approx.)
pdftk in.pdf cat 1-endS output out.pdf
Alternate : pdfsam ( The version in ubuntu respository is old , latest version at http://www.pdfsam.org/downloads/ )
===========
- Youtube download as mp3
1) To install it right away for all UNIX users (Linux, OS X, etc.), type:
sudo curl -L https://yt-dl.org/downloads/latest/youtube-dl -o /usr/local/bin/youtube-dl
sudo chmod a+rx /usr/local/bin/youtube-dl
2) If you do not have curl, you can alternatively use a recent wget:
sudo wget https://yt-dl.org/downloads/latest/youtube-dl -O /usr/local/bin/youtube-dl
sudo chmod a+rx /usr/local/bin/youtube-dl
3) The command (requires ffmpeg package) : youtube-dl --prefer-ffmpeg --extract-audio --audio-format mp3 --audio-quality 0 "<video_watch_url>"
==========
- Convert video file to lossless flac format
ffmpeg -i "input.mkv" -vn -sn -acodec flac audio.flac
==========
- Convert video file to mp3 format
ffmpeg -i "input.mkv" -vn -sn -acodec mp3 audio.mp3
