How to run multiple dd commands in background & see status?

I want to run multiple dd commands in background, but be able to see the status.

I have the following script.sh:

#!/usr/bin/env bash

for drive in $@
do
  echo "Wiping $drive"
  dd if=/dev/zero of=$drive status=progress &
done
wait
echo "Done."

Which results in the following output:

$ sudo bash ./script.sh /dev/sda /dev/sdb
Wiping /dev/sda
Wiping /dev/sdb
288788992 bytes (289 MB, 275 MiB) copied, 10 s, 28.9 MB/s 14404864 bytes (114 MB, 109 MiB) copied, 4 s, 28.6 MB/s

Is there any way how to output the respective dd statuses below the drive paths? For example:

$ sudo bash ./script.sh /dev/sda /dev/sdb
Wiping /dev/sda
288788992 bytes (289 MB, 275 MiB) copied, 10 s, 28.9 MB/s
Wiping /dev/sdb
14404864 bytes (114 MB, 109 MiB) copied, 4 s, 28.6 MB/s

I tried various redirects, named pipes etc. but wasn't able to achieve such (or similar) output.

---

I tried the coprocesses approach which seems to be the way to go, but now I'm unable to make it work with the for cycle.

This works fine:

coproc dd_sda { dd if=/dev/zero of=/dev/sda status=progress 2>&1; }
echo "sda PID: $dd_sda_PID"
coproc dd_sdb { dd if=/dev/zero of=/dev/sdb status=progress 2>&1; }
echo "sdb PID: $dd_sdb_PID"

sda PID: 12494
./wipe.sh: line 86: warning: execute_coproc: coproc [12494:dd_sda] still exists
sdb PID: 12496

However this:

for drive in sda sdb
do
  coproc_name=dd_${drive}
  coproc $coproc_name { dd if=/dev/zero of=/dev/$drive status=progress 2>&1; }
  pid_var="${coproc_name}_PID"
  echo "$drive PID: ${!pid_var}"
done

doesn't work for the second coprocess:

sda PID: 12759
./wipe.sh: line 39: warning: execute_coproc: coproc [12759:dd_sda] still exists
sdb PID: 

When hardcoding the name using if condition, it also works:

for drive in sda sdb
do
  coproc_name=dd_${drive}
  if [[ "$drive" == 'sda' ]]
  then
    coproc dd_sda { dd if=/dev/zero of=/dev/$drive status=progress 2>&1; }
  elif [[ "$drive" == 'sdb' ]]
  then
    coproc dd_sdb { dd if=/dev/zero of=/dev/$drive status=progress 2>&1; }
  fi
  pid_var="${coproc_name}_PID"
  echo "$drive PID: ${!pid_var}"
done

sda PID: 12998
./wipe.sh: line 39: warning: execute_coproc: coproc [12998:dd_sda] still exists
sdb PID: 13000

Here is my final solution, massively inspired by @Diego Torres Milano (thanks again).

#!/usr/bin/env bash

drives=$@
number_of_drives=$#
drives_to_wipe=($drives)

stripped_drive_path() {
  echo $1 | awk -F/ '{ print $3 }'
}

wipe() {
  echo "Filling \`$1\` drive with zeros:"
  dd if=/dev/zero of=$1 status=progress 2>&1
}

echo "Total number of drives: $number_of_drives"

# Wipe the drives in parallel

iteration=1
for drive in $drives; do
  drive_name=$(stripped_drive_path $drive)
  coproc_name=dd_${drive_name}
  eval coproc $coproc_name "{ wipe $drive; }"
  if [[ "$iteration" == 1 ]]; then
    echo 'Feel free to ignore the following warnings'
  fi
  ((iteration++))
done

# Display the progress

iteration=1
# Run until all drives are wiped
while [[ ${#drives_to_wipe[@]} > 0 ]]; do
  for drive in $drives; do
    drive_name=$(stripped_drive_path $drive)
    coproc_name=dd_${drive_name}

    # Move one line below the "Filling drive with zeros" message
    if [[ $iteration > 1 ]]; then
      tput cud 1
    fi

    # Read the drive's current status from the coprocess
    if read -r -d $'\r' -u ${!coproc_name[0]} line &> /dev/null; then
      tput el # Clear line
      echo -e "$line\r\n"
    else
      # Remove the finished drive from the list
      for i in ${!drives_to_wipe[@]}; do
        if [ "${drives_to_wipe[$i]}" == "$drive" ]; then
          unset drives_to_wipe[$i]
        fi
      done
      tput el # Clear line
      echo -e "$(($number_of_drives - ${#drives_to_wipe[@]}))/$number_of_drives done!\r\n"
    fi

    # Move back one line up
    if [[ $iteration > 1 ]]; then
      tput cuu 1
    fi

  done

  # Move two lines up for each drive
  if [[ ${#drives_to_wipe[@]} > 0 ]]; then
    tput cuu $(($number_of_drives * 2))
  fi

  ((iteration++))
done

echo "All drives ($number_of_drives) wiped."

Which results in such output:

$ sudo bash ./script.sh /dev/sda /dev/sdb
Total number of drives: 2
Feel free to ignore the following warnings
./wipe.sh: line 24: warning: execute_coproc: coproc [85994:dd_sda] still exists
Filling `/dev/sda` drive with zeros:
1/2 done!
Filling `/dev/sdb` drive with zeros:
2/2 done!
All drives (2) wiped.