Shell Programming and Scripting

00012919 7836049      S
00012920 7836049      S
00012921 3828157      Y
00012922 3828157      Y
00012923 3828157      S
T005290070331000012923

00012923 3824017      Y
00012924 3820067      S

00012919 7836049      S
00012920 7836049      S
00012921 3828157      Y
00012922 3828157      Y
00012923 3828157      S
00012924 3824017      Y
00012925 3820067      S
T005290070331000012925

awk '
/^[0-9]/ && FNR == NR {
        # Copy lines from 1st file (before the last line) to the output.
        last = $1       # Save the sequence number in the 1st field.
        print
        next
}
/^F/ {  final = $0;next}        # Save the last line from the 1st file.
{       # Replace the seqnece number in lines from the 2nd file and print
        # the modified lines...
        printf("%08d%s\n", ++last, substr($0, 9))
}
END {   # Replace the sequence number at the end of the last record in the 1st
        # file with the last sequence number assigned to new records from the
        # 2nd file.
        printf("%s%08d\n", substr(final, 1, length(final) - 8), last)
}' file add