Question

Below is the sample code,

top_dir=(network_dir telecomm_dir)
network_dir=(dijkstra patricia)
telecomm_dir=(CRC32 FFT adpcm gsm)

for bench in ${top_dir[@]}; do
  for subdir in ${$bench[@]}; do
    make -C $subdir
  done
done

What I have is two directories, each of them has subdirectories. I want to iterate each directory and do make. When I run this script, it give me the error message,

./run.sh: line 21: ${$bench[@]}: bad substitution

Is it possible to let bash use variable ”bench” to access network_dir and telecomm_dir? Thanks!

Answer 1

one option is to use dereferencing

top_dir=(network_dir telecomm_dir)
network_dir=(dijkstra patricia)
telecomm_dir=(CRC32 FFT adpcm gsm)

for bench in "${top_dir[@]}"; do
  arr="${!bench}"
  for subdir in "${arr[@]}"; do
    make -C "$subdir"
  done
done

also use more quotes

---

another option is to use associative arrays:

declare -A dirs=(
    [network_dir]="dijkstra patricia"
    [telecomm_dir]="CRC32 FFT adpcm gsm"
)

for bench in "${!dirs[@]}"; do
    for subdir in ${dirs[$bench]}; do  # requires subdirs with no spaces
        make -C "$subdir"
    done
done