# uniq.awk --- do uniq in awk

#

# Requires getopt() and join() library functions

#

# Arnold Robbins, arnold@skeeve.com, Public Domain

# May 1993

function usage()

{

    print("Usage: uniq [-udc [-n]] [+n] [ in [ out ]]") > "/dev/stderr"

    exit 1

}

# -c    count lines. overrides -d and -u

# -d    only repeated lines

# -u    only nonrepeated lines

# -n    skip n fields

# +n    skip n characters, skip fields first

BEGIN {

    count = 1

    outputfile = "/dev/stdout"

    opts = "udc0:1:2:3:4:5:6:7:8:9:"

    while ((c = getopt(ARGC, ARGV, opts)) != -1) {

        if (c == "u")

            non_repeated_only++

        else if (c == "d")

            repeated_only++

        else if (c == "c")

            do_count++

        else if (index("0123456789", c) != 0) {

            # getopt() requires args to options

            # this messes us up for things like -5

            if (Optarg ~ /^[[:digit:]]+$/)

                fcount = (c Optarg) + 0

            else {

                fcount = c + 0

                Optind--

            }

        } else

            usage()

    }

    if (ARGV[Optind] ~ /^\+[[:digit:]]+$/) {

        charcount = substr(ARGV[Optind], 2) + 0

        Optind++

    }

    for (i = 1; i < Optind; i++)

        ARGV[i] = ""

    if (repeated_only == 0 && non_repeated_only == 0)

        repeated_only = non_repeated_only = 1

    if (ARGC - Optind == 2) {

        outputfile = ARGV[ARGC - 1]

        ARGV[ARGC - 1] = ""

    }

}

function are_equal(    n, m, clast, cline, alast, aline)

{

    if (fcount == 0 && charcount == 0)

        return (last == $0)

    if (fcount > 0) {

        n = split(last, alast)

        m = split($0, aline)

        clast = join(alast, fcount+1, n)

        cline = join(aline, fcount+1, m)

    } else {

        clast = last

        cline = $0

    }

    if (charcount) {

        clast = substr(clast, charcount + 1)

        cline = substr(cline, charcount + 1)

    }

    return (clast == cline)

}

NR == 1 {

    last = $0

    next

}

{

    equal = are_equal()

    if (do_count) {    # overrides -d and -u

        if (equal)

            count++

        else {

            printf("%4d %s\n", count, last) > outputfile

            last = $0

            count = 1    # reset

        }

        next

    }

    if (equal)

        count++

    else {

        if ((repeated_only && count > 1) ||

            (non_repeated_only && count == 1))

                print last > outputfile

        last = $0

        count = 1

    }

}

END {

    if (do_count)

        printf("%4d %s\n", count, last) > outputfile

    else if ((repeated_only && count > 1) ||

            (non_repeated_only && count == 1))

        print last > outputfile

    close(outputfile)

}