Useful One-liners Computer Commands


List hidden folders

ls -la | awk '{print $9}' | grep "^\." | grep -v "\.$" | grep -v "^.vtools"

Terminal colored text

echo -e "\e[1;34mThis is bold blue text.\e[0m"
echo -e "\e[4;31mThis is underlined red text.\e[0m"

Find large files

sudo find /itch -size +20G -exec du -h {} \; > LargeFiles.txt

Find and remove folders

find . -type d -name ".svn" -exec rm -r {} \;
find . -name .svn -print0 | xargs -0 rm -r

Find and replace pattern from all files

perl -pi.bak -e 's/sample_variant_/genotype_/g' *.py
perl -pi.bak -e 's/@@@\\\(/{\$\\\(/g' *.notes
perl -pi.bak -e 's/\\\)@@@/\\\)\$}/g' *.notes
perl -pi.bak -e 's/\\\]@@@/\\\]\$}/g' *.notes
perl -pi.bak -e 's/@@@\\\[/{\$\\\[/g' *.notes

Figure out and add file extension

find . -type f -not -name "*.*" -print0 | xargs -0 file | grep  'JPEG image data' | sed 's/:.*//' | xargs -I % echo mv % %.jpg >


Change folder to 755, file to 644

find . -type f -print0 | xargs -I {} -0 chmod 0644 {}
find . -type d -print0 | xargs -I {} -0 chmod 0755 {}


shred -n 200 -z -u  personalinfo.tar.gz
shred -vfz -n 10 /dev/sda5

awk and sed

awk sum

cut -d" " -f5 LargeFile.txt | sed 's/G//' | awk 'BEGIN{sum=0}{sum += $1}END{print sum}'
cut -d" " -f5 LargeFile.txt | sed 's/G//' | awk 'BEGIN{sum=0}{sum += $1}END{print sum/NR}'

Remove the first line of file

Generate new file

sed 1d delete_old_capture_file.dump > delete_old_capture_file.list

Update same file

sed -i 1d /tmp/delete_old_capture_file.dump

PDF, images and videos

Combine / split PDFs

gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=combinedpdf.pdf -dBATCH 1.pdf 2.pdf 3.pdf
pdftk *.pdf cat output combined.pdf
pdftk combinedpdf.pdf burst

Resize photo

find ./ -name '*.jpg' -exec convert -resize 600x480 {} {} \;

Image file conversion

convert 1.pdf 1.jpg -density 250

JVC mod file to mp4

ffmpeg -i MOV001.MOD -vcodec copy -acodec copy -f mp4 1.mp4

Extract clip from video

avconv -ss <start-time> -i long-video.mp4 -codec copy -t <duration> important-clip.mp4
ffmpeg -ss 00:32:15 -t 00:00:48 -i long-video.mp4 -vcodec copy -acodec copy important-clip.mp4

MOV to mp4

avconv -i 09380001.MOV  -acodec aac -strict experimental -ab 128k -vb 3000k -f mp4 carcam-`date +%Y%m%d`.mp4

Multi-line recipe

Output duplicated lines

For example based on the 2nd column duplicate. The awk script is

  BEGIN { FS = "\t" }
      # Keep count of the fields in second column
      # Save the line the first time we encounter a unique field
      if (count[$2] == 1)
          first[$2] = $0;
      # If we encounter the field for the second time, print the
      # previously saved line
      if (count[$2] == 2)
          print first[$2];
      # From the second time onward. always print because the field is
      # duplicated
      if (count[$2] > 1)


cut -f1,4,5,6 *.bim | sort -g -k2 | awk -f dup.awk