Some testcases for concurrent background jobs and pipe I/O

out

a: 1 2 1 2 1 1 2 1 2 1 2 1 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 2 1 2 1=16 2=14
b: 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 2 1 2 1 2 1 2 1 2 1 2 1 2 1=14 2=16
c: 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 1=15 2=15
d: 2 1 1 2 1 2 1 1 2 1 2 1 2 1 1 2 1 1 2 1 2 1 1 2 1 2 1 1 2 1 1=18 2=12
e: 3 2 3 2 3 2 3 2 3 2 3 2 3 3 2 3 2 3 2 3 2 3 2 3 2 3 2 3 3 2 2=14 3=16
f: 2 2 1 2 1 2 1 2 1 2 2 1 2 1 2 1 1 2 1 2 1 2 2 1 2 1 2 1 2 1 1=14 2=16

pipefork.bash

#!/usr/bin/env bash

function compatFixes {
    ${BASH_VERSION+shopt -s extglob lastpipe}

    if [[ ${!KSH_VERSION} == .sh.version ]]; then
        function read {
            command read "${@/#*(-[^a])a*(?)/\1A\2}"
        }
    fi
}

# Functions share a stream of zeros.
function zeros {
    printf '%.s0' {1..30}
}

# Reader function.
function z {
    typeset -li x=
    while IFS= read -rN1 _; do
        ((x++))
        printf %-2d "$1" # keep track of which job this is.
    done
}

# read, format, print output from z jobs
function out {
    typeset -lia totals=() zs=()
    read -ra zs
    printf %-2s "${zs[@]}"

    typeset -li x=
    for x in "${zs[@]}"; do
        ((totals[x]++))
    done

    printf %s "${clrs[green]}"
    for x in "${!totals[@]}"; do
        printf '%s=%s ' "$x" "${totals[x]}"
    done
    printf '%s\n' "${clrs[reset]}"
}

### example funcs ###

# For some reason Bash doesn't require an explicit <&0 in this case.
function a {
    out < <({ z 1 & z 2; } < <(zeros))
}

# As above, with piped output.
function b {
    { z 1 <&0 & z 2; } < <(zeros) | out
}

# Same as b.
function c {
    zeros | { z 1 <&0 & z 2; } | out
}

# Like the above two. Redirect to each z individually. Now behaves as the first example again.
function d {
    typeset x
    { z 1 <&$x & z 2 <&$x; } {x}< <(zeros) | out
}

# The first command in the list to be explicitly redirected to the proper input,
# and all subsequent members, are asynchronous as expected.
function e {
    typeset x
    { z 1 & z 2 <&$x & z 3 & } {x}< <(zeros) <&$x | out
}

# Pass the name of the pipe to g and individually redirect to z. Doesn't work.
# Pipe is closed before the second call to f sees it:
function f {
    function g { z 1 & z 2; } <"$1"
    g <(zeros) | out
    unset -f g
}

function main {
    compatFixes

    typeset -A clrs=(
        [green]="$(tput setaf 2)"
        [reset]="$(tput sgr0)"
    )

    typeset fn 
    for fn; do
        printf '%s: ' "$fn"
        "$fn"
    done
}

main {a..f}

# vim: set fenc=utf-8 ff=unix ts=4 sts=4 sw=4 ft=sh et: