scripting help with bash and awk

Shell Programming and Scripting
1

I'm trying to reformat some tide information into a useable format and failing.
Input file is....

4452 CHENNAI (MADRAS)
13�06'N, 80�18'E India East Coast 01 June 2009 UT(GMT)
Data Area 3. Indian Ocean (northern part) and Red Sea to Singapore

01/06/2009
00:00 0.7 m
00:20 0.7 m
00:40 0.7 m
01:00 0.6 m
01:20 0.6 m
01:40 0.6 m
02:00 0.5 m
02:20 0.5 m
etc
22:00 0.9 m
22:20 0.9 m
22:40 0.9 m
23:00 0.9 m
23:20 0.9 m
23:40 0.9 m
02/06/2009
00:00 0.9 m
00:20 0.8 m
00:40 0.8 m
01:00 0.8 m
01:20 0.8 m
01:40 0.7 m
etc
22:20 0.9 m
22:40 0.9 m
23:00 0.9 m
23:20 0.9 m
23:40 1.0 m
03/06/2009
00:00 1.0 m
00:20 1.0 m
00:40 0.9 m
01:00 0.9 m
01:20 0.9 m
01:40 0.9 m
etc
22:20 0.8 m
22:40 0.8 m
23:00 0.9 m
23:20 0.9 m
23:40 1.0 m
Predicted heights are in metres above Chart Datum
Printed by TotalTide

etc just means that I have taken out values for display purposes, time increment by 20 minutes all day.

The output file I want is three columns; julian day, 24hr time and tide correction as below..

key key
day hourmin tide
152 0000 0.7
152 0020 0.7
152 0040 0.7
152 0100 0.6
152 0120 0.6
152 0140 0.6
152 0200 0.5
152 0220 0.5
etc
152 2200 0.9
152 2220 0.9
152 2240 0.9
152 2300 0.9
152 2320 0.9
152 2340 0.9
153 0000 0.9
153 0000 0.8
153 0040 0.8
153 0100 0.8
153 0120 0.8
153 0140 0.7
etc
153 2220 0.9
153 2240 0.9
153 2300 0.9
153 2320 0.9
153 2340 1.0
154 0000 1.0
154 0020 1.0
154 0040 0.9
154 0100 0.9
154 0120 0.9
154 0140 0.9
etc
154 2220 0.8
154 2240 0.8
154 2300 0.9
154 2320 0.9
154 2340 1.0

Thank you in advance people

2

what have you tried till now??

3 
gawk -F'[/: ]' '
/^..\/..\/..../{j=strftime("%j",mktime($3" "$2" "$1" 00 00 00"))}
/^..:../{print j,$1$2,$3}
' infile > outfile
4

here is my attempt...a very ugly script and not very portable but seems to do the job now.....
thanks for your input....all sorted now....thanks

fold input_file| egrep "^ [0-2]" > tides1
nl tides1 > tides2
awk 'BEGIN{print "key key"
print "day hourmin tide" }
{printf "%d %s%s %s\n",($1/73 + 152), substr($2,1,2),substr($2,4,5), $3}' tides2 > output_file
rm tides1 tides2

-----Post Update-----

here is my attempt...a very ugly script and not very portable but seems to do the job now.....
thanks for your input....all sorted now....thanks

fold input_file| egrep "^ [0-2]" > tides1
nl tides1 > tides2
awk 'BEGIN{print "key key"
print "day hourmin tide" }
{printf "%d %s%s %s\n",($1/73 + 152), substr($2,1,2),substr($2,4,5), $3}' tides2 > output_file
rm tides1 tides2