tldr/pages/linux/coproc.md

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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"