Bash Script 유용한 Tip

Bash Script 유용한 Tip

1. 파라매터 설정
1. 출처 : http://wiki.bash-hackers.org/syntax/pe

2. Looking for a specific syntax you saw, without knowing the name?

   • Simple usage

     • $PARAMETER

     • ${PARAMETER}

   • Indirection

     • ${!PARAMETER}

   • Case modification

     • ${PARAMETER^}

     • ${PARAMETER^^}

     • ${PARAMETER,}

     • ${PARAMETER,,}

     • ${PARAMETER~}

     • ${PARAMETER~~}

   • Variable name expansion

     • ${!PREFIX*}

     • ${!PREFIX@}

   • Substring removal (also for filename manipulation!)

     • ${PARAMETER#PATTERN}

     • ${PARAMETER##PATTERN}

     • ${PARAMETER%PATTERN}

     • ${PARAMETER%%PATTERN}

   • Search and replace

     • ${PARAMETER/PATTERN/STRING}

     • ${PARAMETER//PATTERN/STRING}

     • ${PARAMETER/PATTERN}

     • ${PARAMETER//PATTERN}

   • String length

     • ${#PARAMETER}

   • Substring expansion

     • ${PARAMETER:OFFSET}

     • ${PARAMETER:OFFSET:LENGTH}

   • Use a default value

     • ${PARAMETER:-WORD}

     • ${PARAMETER-WORD}

   • Assign a default value

     • ${PARAMETER:=WORD}

     • ${PARAMETER=WORD}

   • Use an alternate value

     • ${PARAMETER:+WORD}

     • ${PARAMETER+WORD}

   • Display error if null or unset

     • ${PARAMETER:?WORD}

     • ${PARAMETER?WORD}