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coproc utility is not the same as utility & in bash.

With coproc utility you get an array, COPROC, that contains the standard input and output filedescriptors of utility. You may then do things like

#!/bin/bash

coproc bc -l

for (( k = 0; k < 50; ++k )); do
  printf '2.3*%d + 1\n' "$k" >&${COPROC[1]}
  read -u "${COPROC[0]}" a
  printf '%.2f\n' "$a"
done

kill "$COPROC_PID"

Here, bc -l is a co-process and acts like a "arithmetic computation service" for the shell loop, taking expressions to compute on its standard input and giving back results on its standard output.

As far as I can tell, bash also only supports one co-process at any one time.

The ksh93 shell also supports co-processes, but the syntax is totally different (but somewhat sleeker). This is the equivalent ksh93 script:

#!/usr/bin/ksh93

bc -l |&

for (( k = 0; k < 50; ++k )); do
  print -p -f '2.3*%d + 1\n' "$k"
  read -p a
  printf '%.2f\n' "$a"
done

Here, it's the -p option to print and read that makes it communicate with the co-process (the process started with |&) rather than using some explicit filedescriptor.

coproc utility is not the same as utility & in bash.

With coproc utility you get an array, COPROC, that contains the standard input and output filedescriptors of utility. You may then do things like

#!/bin/bash

coproc bc -l

for (( k = 0; k < 50; ++k )); do
  printf '2.3*%d + 1\n' "$k" >&${COPROC[1]}
  read -u "${COPROC[0]}" a
  printf '%.2f\n' "$a"
done

kill "$COPROC_PID"

Here, bc -l is a co-process and acts like a "arithmetic computation service" for the shell loop, taking expressions to compute on its standard input and giving back results on its standard output.

As far as I can tell, bash also only supports one co-process at any one time.

The ksh93 shell also supports co-processes, but the syntax is totally different (but somewhat sleeker). This is the equivalent ksh93 script:

#!/usr/bin/ksh93

bc -l |&
coproc_pid=$!

for (( k = 0; k < 50; ++k )); do
  print -p -f '2.3*%d + 1\n' "$k"
  read -p a
  printf '%.2f\n' "$a"
done

kill "$coproc_pid"

Here, it's the -p option to print and read that makes it communicate with the co-process (the process started with |&) rather than using some explicit filedescriptor.

coproc utility is not the same as utility & in bash.

With coproc utility you get an array, COPROC, that contains the standard input and output filedescriptors of utility. You may then do things like

#!/bin/bash

coproc bc -l

for (( k = 0; k < 50; ++k )); do
  printf "2.3*%d + 1\n" "$k" >&${COPROC[1]}
  read -u "${COPROC[0]}" a
  printf '%.2f\n' "$a"
done

kill "$COPROC_PID"

Here, bc -l is a co-process and acts like a "arithmetic computation service" for the shell loop, taking expressions to compute on its standard input and giving back results on its standard output.

As far as I can tell, bash also only supports one co-process at any one time. The ksh93 shell also supports co-processes, but the syntax is totally different (but somewhat sleeker).

coproc utility is not the same as utility & in bash.

With coproc utility you get an array, COPROC, that contains the standard input and output filedescriptors of utility. You may then do things like

#!/bin/bash

coproc bc -l

for (( k = 0; k < 50; ++k )); do
  printf '2.3*%d + 1\n' "$k" >&${COPROC[1]}
  read -u "${COPROC[0]}" a
  printf '%.2f\n' "$a"
done

kill "$COPROC_PID"

Here, bc -l is a co-process and acts like a "arithmetic computation service" for the shell loop, taking expressions to compute on its standard input and giving back results on its standard output.

As far as I can tell, bash also only supports one co-process at any one time.

The ksh93 shell also supports co-processes, but the syntax is totally different (but somewhat sleeker). This is the equivalent ksh93 script:

#!/usr/bin/ksh93

bc -l |&

for (( k = 0; k < 50; ++k )); do
  print -p -f '2.3*%d + 1\n' "$k"
  read -p a
  printf '%.2f\n' "$a"
done

Here, it's the -p option to print and read that makes it communicate with the co-process (the process started with |&) rather than using some explicit filedescriptor.

coproc utility is not the same as utility & in bash.

With coproc utility you get an array, COPROC, that contains the standard input and output filedescriptors of utility. You may then do things like

#!/bin/bash

coproc bc -l

for (( k = 0; k < 50; ++k )); do
  printf "2.3*%d + 1\n" "$k" >&${COPROC[1]}
  read -u "${COPROC[0]}" a
  printf '%.2f\n' "$a"
done

kill "$COPROC_PID"

Here, bc -l is a co-process and acts like a "arithmetic computation service" for the shell loop, taking expressions to compute on its standard input and giving back results on its standard output.

coproc utility is not the same as utility & in bash.

With coproc utility you get an array, COPROC, that contains the standard input and output filedescriptors of utility. You may then do things like

#!/bin/bash

coproc bc -l

for (( k = 0; k < 50; ++k )); do
  printf "2.3*%d + 1\n" "$k" >&${COPROC[1]}
  read -u "${COPROC[0]}" a
  printf '%.2f\n' "$a"
done

kill "$COPROC_PID"

Here, bc -l is a co-process and acts like a "arithmetic computation service" for the shell loop, taking expressions to compute on its standard input and giving back results on its standard output.

As far as I can tell, bash also only supports one co-process at any one time. The ksh93 shell also supports co-processes, but the syntax is totally different (but somewhat sleeker).