hi

Assuming that

1. $line is a line you've read from your text file, and that
2. a newline is your record delimiter, and that
3. your fields' content never contains tabs:

$line =~ s/\t+/\t/g;
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The + modifier to the \t tells the regular expression to find one or more of the preceding thingie (in this case, a tab). The g modifier at the end tells the regular expression to perform the substitution on all occurrences of the match.

HTH