one-liners.md

• Use paste and bc to add up a column of numbers:

  du -s *.pdf | cut -f 1 | paste -sd+ - | bc

• Pretty diff: diff -y -W $(tput cols) file1 file2 | colordiff | less -R

• Find non-ascii characters in vim: /[^\x00-\x7F]

• Generate a 256-bit random number: xxd -l 32 -c 32 -p /dev/random

• Extract metadata from a media file:

  ffprobe -v quiet \
    -show_entries format_tags=artist,album,track,title:format=bit_rate \
    -print_format json $filename

• Make say speak all the voice options:

  say -v ? | awk '{split($0, a, "#"); system("say -v \""$1"\" \""a[2]"\" ")}'
  

• Get width and height of an image: identify -format '%w %h %i\n' in.jpg

• Shrink image to fit within bounds: convert -geometry "700x700>" in.jpg out.jpg

• svg to png: rsvg-convert -d 180 -p 180 -o out.png in.svg

• Sync files from a webserver:

  wget --mirror --accept=pdf --progress=dot \
       --no-host-directories --no-parent $url
  

• Run desktop over SSH: Xnest -geometry 1150x750 :1 & DISPLAY=:1 gnome-session

• Very fast downloads: aria2c --file-allocation=none -c -x 10 -s 10 "$url"

• Fix image orientation: jhead -autorot image.jpg

• Print via CUPS server:

  lp -h [cups-host] -d HP-LaserJet-P2055dn -o InputSlot=Tray2 -o fit-to-page [filename]
  

• Run tests many times to test for infrequent errors:

  for n in {1..100}; do py.test > /dev/null && echo 'pass' || echo 'fail' ; done | tee results.txt

• Add text to a video stream:

  ffmpeg -i http://10.109.2.135/mpeg4 \
         -vcodec libx264 \
         -vf "drawtext=textfile=/tmp/text:x=0:y=h/10*mod(t\,10):reload=1:fontcolor=yellow" \
         -f mpegts udp://0.0.0.0:1234
  

• rsync only specific file types:

  rsync -aP -f '+ *.html' -f '+ *.js' -f '+ */' -f '- *' src/ dest
  

• tar only specific file types:

  find src -name '*.html' -o -name '*.js' | tar -cf dest.tar -T -
  

• Print all console colours:

  for i in {0..255}; do printf " %03d: " $i; tput setab $i; echo -n "     "; tput sgr0; done