bash script 常用變數技巧

   Bash basic concepts

   http://wiki.bash-hackers.org/scripting/basics

  Bash script parameter substitution

   http://tldp.org/LDP/abs/html/parameter-substitution.html

 ${!varprefix*}, ${!varprefix@}

Matches names of all previously declared variables beginning with varprefix.

# This is a variation on indirect reference, but with a * or @. # Bash, version 2.04, adds this feature. xyz23=whatever xyz24= a=${!xyz*} # Expands to *names* of declared variables # ^ ^ ^ + beginning with "xyz". echo "a = $a" # a = xyz23 xyz24 a=${!xyz@} # Same as above. echo "a = $a" # a = xyz23 xyz24 echo "---" abc23=something_else b=${!abc*} echo "b = $b" # b = abc23 c=${!b} # Now, the more familiar type of indirect reference. echo $c # something_else

from 鳥哥