coproc

Bash builtin for creating interactive asynchronous subshells. More information: https://www.gnu.org/software/bash/manual/bash.html#Coprocesses.

coproc { command1; command2; ...; }

coproc name { command1; command2; ...; }

echo "input" >&"${name[1]}"

read variable <&"${name[0]}"

coproc name { while read line; do command1; command2; ...; done }

coproc BC { bc --mathlib; }; echo "1/3" >&"${BC[1]}"; read output <&"${BC[0]}"; echo "$output"