rc/sh/running

#!/usr/bin/env sh
# compat: +ash +bash +dash +zsh YES_BB_AWK

# probably not compatible with busybox ps because its column 2 isn't PID.

running() { ### @- WIP
    local cmd=0 pid=0 col=
    local usage='usage: running {cmd|pid} ...'
    [ $# -gt 0 ] || { printf '%s\n' "$usage" >&2; return 2; }
    for col; do
        case "$col" in
        (cmd) cmd=1;;
        (pid) pid=1;;
        (*) printf '%s\n' "$usage" >&2; return 2;;
        esac
    done

    # ps -o pid,comm=CMD
    # argumentless flags accepted by busybox:
    #   a   d e f       l                   A               T     Z
    # argumentless flags accepted by coreutils:
    #   a c d e f g h j l m n r s t u v w x A F H L M N P S T V X Z

    ps -f | awk -v cmd=$cmd -v pid=$pid '
    NR==1{
        s=index($0,"COMMAND")
        s=s?s:index($0,"CMD")
    }
    NR>1{
        l=substr($0,s)
        sub(" .*","",l)
        sub(".*[/\\\\]","",l)
        if(pid)printf "%s", $2
        if(cmd&&pid)printf "\t"
        if(cmd)printf "%s", l
        printf "\n"
    }
    '
}

[ -n "${preload+-}" ] || running "$@"