Drop the quotation marks (the ones inside the qw): 
$object->stty(qw(cols 200));

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What you have is passing "cols and 200" to stty, which it does not recognize (as indicated in the error messages). Also note that according to the docs, you probably want to be using the slave side of the pty: 
$object->slave->stty(qw(cols 200));

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In reply to Re^3: Expect.pm control terminal width by broomduster
in thread Expect.pm control terminal width by jmclark

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