Why is line solid?

I typ开发者_StackOverflowe in gnuplot "plot cos(x) lt 2" and want to take dashed line, but I take only solid line. I use gnuplot 4.2 and ubuntu 10.04

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It depends on the Terminal being used via

set term TYPE_OF_TERMINAL OPTIONS

Some Terminals are unable to display dashed lines.
You would see Terminal being set at the start: Terminal type set to 'TYPE_OF_TERMINAL'

example for ps/eps : set term postscript eps enhanced
At least this way you can include it in your TeX documents.