I am trying to do an indirect reference to values in an array in bash.
anotherArray=("foo" "faa")
foo=("bar" "baz")
faa=("test1" "test2")
for indirect in ${anotherArray[@]}
do
echo ${!indirect[0]}
echo ${!indirect[1]}
done
This does not work. I tried a lot of differenct things to get the different values of $foo by echoing $indirect but I can only get the first value, all values, '0' or nothing at all.
You have to write the index in the variable used for indirection :
anotherArray=("foo" "faa")
foo=("bar" "baz")
faa=("test1" "test2")
for indirect in ${anotherArray[@]}; do
all_elems_indirection="${indirect}[@]"
second_elem_indirection="${indirect}[1]"
echo ${!all_elems_indirection}
echo ${!second_elem_indirection}
done
If you want to iterate over every element of every arrays referenced in anotherArray, do the following :
anotherArray=("foo" "faa")
foo=("bar" "baz")
faa=("test1" "test2")
for arrayName in ${anotherArray[@]}; do
all_elems_indirection="${arrayName}[@]"
for element in ${!all_elems_indirection}; do
echo $element;
done
done
Alternatively you could directly store the whole indirections in your first array : anotherArray=("foo[@]" "faa[@]")
Modern versions of bash adopt a ksh feature, "namevars", that's a perfect fit for this issue:
#!/usr/bin/env bash
case $BASH_VERSION in ''|[123].*|4.[012]) echo "ERROR: Bash 4.3+ needed" >&2; exit 1;; esac
anotherArray=("foo" "faa")
foo=("bar" "baz")
faa=("test1" "test2")
for indirectName in "${anotherArray[@]}"; do
declare -n indirect="$indirectName"
echo "${indirect[0]}"
echo "${indirect[1]}"
done
You need do it in two steps
$ for i in ${anotherArray[@]}; do
t1=$i[0]; t2=$i[1];
echo ${!t1} ${!t2};
done
bar baz
test1 test2
