like xargs for stdin

xsplit.sh

#!/bin/bash

# todo: keep or discard record separator
# todo: record sep within line?
# todo: line delim param
# todo: print0
# todo: verbose mode showing objects being passed and util being invoked, etc.

VERSTRING='xsplit/v0.2'

RECORD_MODE_NULL=0
RECORD_MODE_LINE=1
RECORD_MODE_RE=2
RECORD_MODE_COUNT=3

COUNT=0
REGEX=''
DELIM=''
RECORD_MODE=$RECORD_MODE_LINE

function print-usage() {
cat <<EOF
Usage: xsplit [-0|-R regex|-n number] [utility [argument ...]]

xsplit finds objects on stdin, piping them individually to <utility>

	-0: expect a null record separator between objects, instead of newline
	-R|--regex [regex]: treat lines matching <regex> as record separators
	-n|--count|--number [number]: Set the maximum number of lines taken from
		standard input for each invocation of utility
	-V|--version: print version information

EOF
}

while [ -n "$1" ]; do
	case "$1" in
		-0)
			RECORD_MODE=$RECORD_MODE_NULL
			;;
		--print0) #not implemented
			;;
		-n|--number|--count)
			COUNT="$2"
			RECORD_MODE=$RECORD_MODE_COUNT
			shift
			;;
		-R|--regex)
			REGEX="$2"
			RECORD_MODE=$RECORD_MODE_RE
			shift
			;;
		-h|-u|--help|--usage)
			print-usage
			true
			exit
			;;
		-V|--version)
			echo "$VERSTRING"
			exit 0
			;;
		*)
			break
			;;
		esac
	shift
done

# set default chunk delimiter
if [[ -z "$DELIM" ]]; then
	case "$RECORD_MODE" in
		$RECORD_MODE_NULL)
			DELIM=$'\0'
			;;
		$RECORD_MODE_LINE|$RECORD_MODE_RE|$RECORD_MODE_COUNT)
			DELIM=$'\n'
			;;
	esac
fi

# set default utility
if [[ -z "$1" ]]; then
	set -- cat
fi

BUF=''
N=0
while read -r -d"$DELIM" line; do

	case "$RECORD_MODE" in
		$RECORD_MODE_COUNT)
			((N++))
			BUF+="$line""$DELIM"
			if [[ $N -eq $COUNT ]]; then
				echo -n "$BUF" | "$@"
				BUF=""
				N=0
			fi
			;;
		$RECORD_MODE_RE)
			BUF+="$line""$DELIM"
			if [[ $line =~ $REGEX ]]; then
				echo -n "$BUF" | "$@"
				BUF=""
			fi		
			;;
		$RECORD_MODE_LINE|$RECORD_MODE_NULL)
			#todo: handle \0 out, maybe with --print0
			printf "%s%c" "$line" "$DELIM" | "$@"
			;;
	esac

done