Content

  1. Shell
    1. Basic Commands
    2. Tips
  2. Editors Usage
    1. Vim
    2. Nano
  3. Shell Scripting
    1. Variables
    2. Conditional Statements
    3. Loops
    4. File Operations

Shell

A command line-interface (CLI) to interact with the computer.

Basic Commands

  • man: Followed by a command, it shows the manual page for that command.
  • mv: Move a file or directory.
  • rm: Remove a file or directory.
  • cat: Concatenate and display the content of a file.
  • fg: resume a paused process.
  • bg: run a process in the background.
  • jobs: list all running processes.

Tips

  • When processing files, use * or ? to represent multiple characters or a single character, respectively. (like cat, rm, mv, etc.)
  • Ctrl + D: exit the shell.
  • Ctrl + Z: to pause a process.
  • chmod +x filename: make a file executable.

Editors Usage

Vim

See the link Vim for more details.

Nano

  • Ctrl + X: exit the editor.
  • Ctrl + G: show the help menu.
  • Ctrl + K: cut a line.
  • Ctrl + U: paste a line.
  • Ctrl + W: search a word.
  • Ctrl + Y: move the cursor to the previous page. Ctrl + V: move the cursor to the next page. Ctrl + A: move the cursor to the beginning of the line. Ctrl + E: move the cursor to the end of the line.

Shell Scripting

Variables

  • $VAR to output the value of VAR (Replace VAR with an expr is also allowed).
  • expr $VAR1 + $VAR2 to evaluate the expressions
  • read VAR to read the input from the user and assign it to VAR

Conditional Statements

  • if [ condition ]; then ... else ... fi

Loops

  • for VAR in $LIST; do ... done

File Operations

  • touch filename: create a file.
  • echo "content" > filename: write content to a file.
  • echo "content" >> filename: append content to a file.
  • sed -i "/$VAR/d" filename: delete a line containing VAR in the file.
  • grep "pattern" filename: search for a pattern in a file and display it