Perl - get first “word” from input string

Question

I am trying to write a Perl program that reads in lines from a text file, and, for each line, extract the first \"word\" from the line, and perform a different action based

Answer 1

This will cover all of your cases and then some:

my ($key, $value) = split /\s*:\s*/, $inputline, 2;

(Or, in English, split $inputline into a maximum of two elements separated by any amount of whitespace, a colon and any amount of whitespace.)

Answer 2

($start) = $inputline =~ /\A([^:\s]+)/;

This will match anything except whitespace and : at the beginning of the line.
Or using split:

($start) = split /[:\s]+/, $inputline, 2;