coproc

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

• Run a subshell asynchronously:

coproc { command1; command2; …; }

• Create a coprocess with a specific name:

coproc name { command1; command2; …; }

• Write to a specific coprocess stdin:

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

• Read from a specific coprocess stdout:

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

• Create a coprocess which repeatedly reads stdin and runs some commands on the input:

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

• Create a coprocess which repeatedly reads stdin, runs a pipeline on the input, and writes the output to stdout:

coproc name { while read line; do echo "$line" | command1 | command2 | … | cat /dev/fd/0; done }

• Create and use a coprocess running bc:

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