# uniq.awk --- do uniq in awk
#
# Requires getopt() and join() library functions
#
# Arnold Robbins, [email protected], Public Domain
# May 1993

function usage( e)
{
e = "Usage: uniq [-udc [-n]] [+n] [ in [ out ]]"
print e > "/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)
}