bash

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About

Collection of various bash commands.

Bash

• Kill/stop all process with particular port

  kill $(ps aux | grep 8888 | awk '{print $2}')
  

• Kill/stop all processes star were started by the VS Code via Remote-SSH:

  ps -ef | grep ".vscode-server" | awk '{print $2}' | xargs kill
  

Ubuntu: various bash commands

• Show linenumners in nano

  nano -l <file>

• Determine number of cores + CPUs

  lscpu | grep -E '^Thread|^Core|^Socket|^CPU\('
  

  echo "Cores = $(( $(lscpu | awk '/^Socket\(s\)/{ print $2 }') * $(lscpu | awk '/^Core\(s\) per socket/{ print $4 }') ))"
  

• List directory as tree (required: apt-get install tree)

  tree .
  tree -a .
  

• Flush disk cache

  sync; echo 3 > /proc/sys/vm/drop_caches

• Shows lines of an output file with grep

  grep -n <pattern> <file>
  cat -n <file> | grep <pattern>

Ubuntu: Configure locale

• To change locale do the following

  sudo locale-gen en_US.utf8
  sudo update-locale LANG=en_US.utf8
  

Ubuntu: disk space problem (e.g., LTS 18.04)

• Determine the space available on the disks (df)

  sudo df -h
  

• Determine the space available on the disks (du)

  • Size on disk (all folders, sorted high -> low)

    sudo du -hsc .* * | sort -rh
    

  • Size on disk

    sudo du -hsc *
    

  • Real size of files

    sudo du -hbc *
    

  • Size of a single folder

    sudo du -sh /var
    

  • Sort output

    sudo du -h | sort -rh
    

• Information about disks

  sudo lsblk -o NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL
  

• Remove some staff

  sudo apt clean # remove cache
  

Ubuntu: Relevant articles

• https://askubuntu.com/questions/1224/how-do-i-determine-the-total-size-of-a-directory-folder-from-the-command-line
• https://askubuntu.com/questions/343066/how-to-delete-a-non-working-kernel-after-update
• https://unix.stackexchange.com/questions/218074/how-to-know-number-of-cores-of-a-system-in-linux
• https://unix.stackexchange.com/questions/19480/how-to-display-line-number-while-doing-grep-on-a-file
• https://www.tecmint.com/learn-nano-text-editor-in-linux/

Configure alias for bash

• How to configure alias-es (add the lines to the end of the file)

  nano ~/.bashrc

• Configure ls

  alias ls='ls --time-style=long-iso --color=tty -Altrh'

• Color the grep-match for easy reading.

  alias grep='grep -inE --color=auto'

• Show linenumners in nano

  alias nano='nano -l'

bash history

• Execute a command without keeping it in history

  <your_secret_command>; history -d $((HISTCMD-1))
  

• Execute a command without keeping it in history (can start your session with)

  export HISTFILE=/dev/null ;history -d $(history 1)
  

• Add timestamp to bash commands (check by calling history)

  echo 'export HISTTIMEFORMAT="%F %T "' >> ~/.bashrc
  

• Relevant articles
  • Execute a command without keeping it in history

Troubleshoot network connection

• Use tcpdump utility to monitor desired ports

  sudo tcpdump port 443 and '(tcp-syn|tcp-ack)!=0'

• Active TCP connections

  netstat -plunt
  

• Display all active Internet connections

  netstat -natp
  

• Find out processes that uses paricular port

  netstat -nlp | grep ':80'
  

zsh

• Install

  sudo apt install zsh
  

• Make default

  chsh -s $(which zsh)
  

• Check if worked

  $SHELL --version
  

• Install and use ohmyzsh
• Relevant articles
  • https://github.com/ohmyzsh/ohmyzsh
  • https://www.sitepoint.com/zsh-tips-tricks/
• zsh + NumLock Issue
  • Check option: Terminal -> Features -> Disable application keypad mode
  • Check option: Terminal > Keyboard > Initial state of numeric pad > Normal
  • Materials
    • https://kb.iu.edu/d/axpf

zsh - issues

Fix issues with keys by editing nano ~/.zshrc text bindkey "^[[H" beginning-of-line bindkey "^[[F" end-of-line

fish

• Install

  sudo apt-add-repository ppa:fish-shell/release-3
  sudo apt-get update && sudo apt-get upgrade
  sudo apt-get install fish
  

• Make default (own user)

  chsh -s /usr/bin/fish
  

• Make default (root)

  sudo chsh -s /usr/bin/fish
  

• Modify $PATH for fish

  fish_add_path /usr/local/bin
  

• Add alias into fish

  alias ls='ls --time-style=long-iso --color=tty -Altrh'
  funcsave ls
  

• Issue with colors in Putty

  set -U fish_color_command cyan
  set -U fish_color_error red --bold
  set -U fish_color_valid_path yellow --bold
  set -U fish_color_option brmagenta --bold
  set -U fish_color_param magenta --bold
  

• Materials
  • https://fishshell.com/docs/3.0/tutorial.html#:~:text=Switching%20to%20fish%3F,usr%2Flocal%2Fbin%2Ffish
  • https://dev.to/iqium/install-fish-shell-on-ubuntu-2204-3337
  • https://fishshell.com/docs/current/tutorial.html#tut_startup
  • https://fishshell.com/docs/current/interactive.html#syntax-highlighting-variables

Linux Utils

• Cheat sheet on Linux Performance

Configurations

• https://www.tecmint.com/restrict-ssh-user-to-directory-using-chrooted-jail/

Useful cli utils

• bat or batcat - syntax highlighting for a large number of programming and markup languages
  • apt install bat
  • https://github.com/sharkdp/bat
• exa -> ls alternative
  • have to be compiled on Ubuntu
  • https://github.com/ogham/exa