• Create several folder with a similar pattern:

  mkdir -p ./folder/subfolder{001,002,003}
  

• Create a symbolic link (source):

  ln -s target link_name
  

• List size in MiB of subfolders and files in the current folder and display them sorted by size:

  du -cm * | sort -nr
  

• Case insensitive search from the current folder of all files that have the string dummy in their filename:

  find ./ -iname "*dummy*"
  

• Recursive and case insensitive content search on non-binary files from the current folder:

  grep -RiI "string to search" ./*
  

• Same as above but only search string in XML files:

  find ./* -iname "*.xml" -exec grep -Hi "string to search" "{}" \;
  

• Find all Jpeg images in the system but exclude /home and /var/lib directory:

  find / -path "/home" -prune -or -path "/var/lib" -prune -or -iname "*.jpg" -print
  

• Get the list of the latest 10 modified files in the current folder tree:

  find ./ -printf "%TY-%Tm-%Td %TT %p\n" | sort | tail -n10
  

• Same as above but sorted by latest access time:

  find ./ -printf "%AY-%Am-%Ad %AT %p\n" | sort | tail -n10
  

• Rename all mp3 files in the current folder by adding a “sub-extension”:

  rename "s/\.mp3/\.my-sub-extension\.mp3/g" *.mp3
  

• Convert all files in the current folder to lower case:

  rename 'y/A-Z/a-z/' *
  

• Display the total size used by all PNG files in sub-directories:

  find ./ -iname "*.png" -exec du -k "{}" \; | awk '{c+=$1} END {printf "%s KB\n", c}'
  

• List all files sharing the same name within the sub folders:

  find . -type f -printf "%f\n" | sort | uniq --repeated --all-repeated=separate
  

Dangerous Commands

• Delete all .pyc and .pyo files in the system:

  find / -name "*.py[co]" | xargs rm
  

• Delete all empty files and folders (run this command several times to remove nested empty directories):

  find . -empty -print -exec rm -rf "{}" \;
  

• Remove empty directories found in all subfolders starting with a dot:

  find . -type d -empty -ipath "./.*" -print -exec rm -rf "{}" \;
  

• I used those commands when I import big quantity of files from a window user:

  find ./* -name "desktop.ini" -print -exec rm -f "{}" \;
  find ./* -name "Thumbs.db" -print -exec rm -f "{}" \;
  

• Delete all files and folders in the current directory except the README.txt file:

  ls ./ -I "README.txt" | xargs rm -rf