And to chuck in an (incredibly primitive) idea for a line count as well: 
_data.txt_
abc:AB CD:100
def:DE FG:101
ghi:GH IJ:102
abc:AB CD:100
ghi:GH IJ:103

my $count;
while ( <FILE> ) {
    print if /^abc:/;
    $count++ if /^abc/;
}
print "Matched $count times\n";

_output_
abc:AB CD:100
abc:AB CD:100
Matched 2 times

[download]
Update: I'm silly; added condition for incrementing $count.

In reply to Re^2: find a string and count of its occurence in a text file by dwu
in thread find a string and count of its occurence in a text file by new@perl

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