Shell Programming

https://youtube.com/playlist?list=PLApuRlvrZKog2XlvGJQh9KY8ePCvUG7Je

• Linux shell
  • cat /etc/shells
  • echo $SHELL
  • chsh
• Bash shell과 변수
  • 변수 선언: varname=value
  • 변수 확인: echo, set
  • 변수 제거: unset varname
  • 환경 변수 선언: export varName=value
  • 환경 변수 확인: env
• Bash shell rule
  • Metacharacters: ₩ ? () $ ... * % {} []
  • Quoting Rule
    • Blackslash (\)
    • Double Quotes (""): 단 $ ''는 제외
    • Single Quotes ('')
  • Nesting Commands
    • $(command)
    • `command`
  • alias
  • Prompt
    • PS1
  • Redirection

    • communication channels	redirection characters
      STDIN	0<
      STDOUT	1>
      STDERR	2>

  • Pipeline
• Bash shell script
  • !#/bin/bash (Shebang, 셔뱅)
  • Sub shell
• Positional Parameters
  • name of shell script: $0
  • first argument: $1
  • second argument: $2
  • number of arguments in $#
  • list of all parameters in $@, $*
  • 로그인 shell의 PID: $$
  • 현재 작업 디렉토리: $PWD
  • 부모 프로세스 ID: $PPID
• Input & Output
  • echo
  • read
  • printf
• Branching
  • exit
  • test
  • if-then
  • case
• Looping
  • expr, let
  • while, until
  • for