You don't need a script for that. You can get your count on the command line:

$ cat 1176022.txt
The foo bar
all of the foo's men
Not here
Foo foo foo
Notfoo
What the foo
Expecting five foos
$
[download]

$ perl -nE '$l++; $i += () = $_ =~ /\bfoo\b/g; say "After line $l: $i"
+' 1176022.txt 
After line 1: 1
After line 2: 2
After line 3: 2
After line 4: 4
After line 5: 4
After line 6: 5
After line 7: 5
$
[download]

See perlrun for Perl's command line switches.