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Bash function creates a persistent subshell of bc to stream multiple arithmetic operations
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| # credit to https://github.com/F-Hauri/Connector-bash for the idea | |
| function bcpipe() { | |
| command -v bc 1>/dev/null 2>&1 || { printf "No bc binary.\n" 1>&2 ; return 1 ;} | |
| [[ $# -lt 1 ]] && { printf "Usage: %s [BCSTART|BCSTOP] || \033[3mbc-compatible arithmetic arguments\033[0m\n" "${FUNCNAME[0]}" ; return 1 ;} | |
| if [[ $1 == "BCSTART" ]] ; then | |
| local tmpd | |
| local tmpfifo | |
| tmpd="$(mktemp -d)" | |
| tmpfifo="$(mktemp -u -p "$tmpd")" | |
| mkfifo -m 0600 "$tmpfifo" | |
| exec {BC_W}> >(exec bc -l >"$tmpfifo") | |
| exec {BC_R}< "$tmpfifo" | |
| rm "$tmpfifo" | |
| rmdir "$tmpd" 1>/dev/null 2>&1 || true | |
| export BC_W | |
| export BC_R | |
| return 0 | |
| fi | |
| if [[ $1 == "BCSTOP" ]] ; then | |
| exec {BC_R}<&- | |
| exec {BC_W}<&- | |
| unset BC_W | |
| unset BC_R | |
| return 0 | |
| fi | |
| local result | |
| if [[ -v BC_R && -v BC_W ]] ; then | |
| printf "%s\n" "$@" 1>&${BC_W} | |
| read -u ${BC_R} result | |
| printf "%s" "$result" | |
| return 0 | |
| else | |
| result="$(printf "%s\n" "$@" | bc -l)" | |
| printf "%s" "$result" | |
| return 0 | |
| fi | |
| } |
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