Shell tips and tricks

• Show parent process id

  ps -o ppid= {pid}
  

• Show process file by name

  ps -p {pid} -o comm=
  

• Show opened ports

  sudo netstat -nlp
  sudo ss -nlpt # or
  

• Sort ps output by memory

  ps aux --sort -rss
  

• Gen certificates pair

  openssl req -nodes -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 9999 -subj '/CN=localhost'
  

• Show certificate expiration

  openssl s_client -showcerts -connect {host}:{port} </dev/null | openssl x509 -noout -dates
  

• Check certificates on match

  openssl x509 -noout -modulus -in server.crt | openssl md5
  openssl rsa -noout -modulus -in server.key | openssl md5
  openssl req -noout -modulus -in server.csr | openssl md5
  

• Change terminal size. Useful for android adb shell

  stty rows 60 cols 156
  

• Full copy directory

  rsync -avxHAX --progress / /new-disk/
  

• Show disk usage by directories inlcude hidden

  du -sch .[!.]* * | sort -h
  

• Round png image

  convert -size 512x512 xc:none -fill white -draw 'roundRectangle 0,0 512,512 50,50' in.png -compose SrcIn -composite rounded.png
  

• ssh tunnel from remote localhost:8080 to local machine localhost:8082

  ssh -N -f -L 8082:localhost:8080 user@remote_ip_address