Reputation: 33635
Consider the following nonsense array:
# KIND[ID]=NAME
MONKEYS[1]="Oo Oo"
MONKEYS[2]="Aa Aa"
MONKEYS[3]="Ba Nana"
LIONS[5]="Mister Mufasa"
LIONS[7]="Cocoa Puff"
LIONS[8]="Lala Leo"
TIGERS[13]="Ben Gal"
TIGERS[15]="Tee Eye Double Guh Err"
TIGERS[22]="Oh Esex Diez Punto Cuatro"
With a given KIND
and ID
, I'm attempting to build a string that resembles $NAME[$ID]
to get the associated name.
When explicitly stating an array name, the command behaves as expected echo "${LIONS[5]}"=>"Mister Mufasa"
). However, whenever a variable is used, the shell responds with the given character in the string.
$LIONS[5] => 'e' # The fifth letter in "Mister Mufasa"
In other cases, I can't find a way to control interpolation to get the NAME
KIND="LIONS"
ID="5"
# Attempt to return value of `LIONS` when `KIND=LIONS`
echo $"${KIND}"; echo "\$${KIND}" #=> "$LIONS"
echo "$${KIND}" #=> "57800{KIND}" Interpolates "$$"
echo "\$\${KIND}"; "\$\${KIND}" #=> "$${KIND}"
I found the following works albeit "ugly"...
eval echo `echo \\$${KIND}`
However when introducing the ID
things break once again:
eval echo `echo \\$${KIND}[$ID]`
#> title:5: no matches found: $LIONS[5]
#> no matches found: $LIONS[5]
I feel like I'm missing something very simple. I have a hunch I'm forgetting to escape something, but I'm not quite sure what.
Also, what "less redundant" alternatives to eval echo `echo...
or eval echo `print...
exist?
Upvotes: 0
Views: 452
Reputation: 126108
In bash, use indirect addressing:
REF="$KIND[$ID]" # Sets REF to "LIONS[5]"
echo "${!REF}" # Prints "Mister Mufasa"
EDIT: In zsh, use nested expansion instead:
echo "${(P)${KIND}[ID]}"
Upvotes: 2