my-join

#! /bin/bash

_my_join_pair=$(dirname $0)/my-join-pair

function usage {
    echo 1>&2 "Usage: $0 [options] file1.txt file2.txt ..."

    echo 1>&2 "-H - input files have headers"
    echo 1>&2 "-c N - Use column N as key in all files"
    echo 1>&2 "-e STR - full outer join and use STR to fill missing fields"
    echo 1>&2 "-h - print help"
    echo 1>&2 "-l - (with -e) left outer join"
    echo 1>&2 "-t CHAR - delimiter (default \\t)"

    exit "$@"
}    

ARGS=()

while getopts 'Hc:e:hlt:' opt ; do
    case "$opt" in
	H) ARGS+=("-H") ;;
	c) ARGS+=("-c" "$OPTARG") ;;
	e) ARGS+=("-e" "$OPTARG") ;;
	h) opt_h=1 ;;
	l) ARGS+=("-l") ;;
	t) ARGS+=("-t" "$OPTARG") ;;
	\?) usage 1 ;;
	*) echo 1>&2 "Can't happen" ; exit 1 ;;
    esac
done
shift $((OPTIND-1))

if [ "$opt_h" ] ; then
    usage
fi

if [ -z "$2" ] ; then
    usage 1
fi

if [ "$2" -a -z "$3" ] ; then
    $_my_join_pair "${ARGS[@]}" $1 $2
    exit
fi

CURR="$1" ; shift 1
DEL=
for f in "$@" ; do
    NEW=$(mktemp)
	$_my_join_pair "${ARGS[@]}" $CURR "$f" > $NEW
    if [ "$DEL" ] ; then
	rm -f $CURR
    fi
    CURR=$NEW
    DEL=1
done
cat $CURR
if [ "$DEL" ] ; then
    rm -f $CURR
fi