Handy commands

By Sachin
October 9, 2016

List of commands for day-to-day use

(Updated on Mar 04, 2017)

SOCKS proxy using SSH

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ssh -N -D 1080 user@server

where

# -N: Do not execute remote commands.
# -D: [bind address:]port. Port in above example.

wget a website

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wget -rkp -l5 -np -nH -cut-dirs=1 https://example.com

where

# -rkp: recursive, make link suitable for local viewing, download all files needed to properly view the page.
# -l5: recursively download 5 links away form the original page.
# -n: retrieve files below parent directory.
# -H: Span across hosts when doing recursive retrieving.

Capture screenshot

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import -window root screenshot.png

Reduce PDF size

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gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -sOutputFile=new_file.pdf original_file.pdf

Unlock PDF file

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gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=unencrypted.pdf -c .setpdfwrite -f encrypted.pdf

Rotate video

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# Using mplayer(watch rotated video)
mplayer -vf-add rotate=1 sample.mp4

# Using ffmpeg
ffmpeg -i infile.mp4 -strict -2 -vf "transpose=1" outfile.mp4

Convert 3GP to MP4

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ffmpeg -i VID_0050.3gp -strict -2 -q:a 0 -ab 64k -ar 44100 VID_0050.mp4

FLV to MP4

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ffmpeg -i input.flv -qscale 1 -ar 22050 output.mp4

Extract audio(MP3) from MP4 video

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ffmpeg -i video.mp4 -f mp3 -ab 192000 -vn music.mp3

# or specify codec to use `libmp3lame` in this case.
ffmpeg -i video.mp4 -f mp3 -codec:a libmp3lame -ab 320000 -vn music.mp3

where

# -i: input file
# -f mp3: file format should be MP3
# -ab 192000: audio should be encoded at 192Kbps. 320000 for 320Kbps
# -vn: don't want video

Cut video by time interval

Cut video starting from 19 min 49 seconds up to 04 mins 18 seconds.

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ffmpeg -y -i Video.mp4 -qscale 1 -ss 00:19:49.0 -t 00:04:18.0 -acodec copy -vcodec copy output.mp4

Note: -sameq was removed in recent version of ffmpeg

Use mplayer to extract audio(MP3)

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mplayer -dumpaudio movie.flv -dumpfile movie_audio_track.mp3

Reduce resolution

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ffmpeg -i Birdman.mp4 -strict -2  -s 720x480 birdman.mp4

recordmydesktop

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recordmydesktop -x 100 -y 100 --width 1280 --height 720 --freq 48000 --fps 30 -o ~/Videos/recordings/test-video.ogv

Include subtitles(Use subtitleeditor to create subtitle)

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ffmpeg -i video.avi -vf subtitles=subtitle.srt out.avi

Resize image 50% of its original size

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convert dragon.gif -resize 50% half_dragon.gif

Control compression level of an image

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convert input.png -quality 75 output.jpg