The -p prints $_ after each line, while -n do not. So the two versions are almost the same (they will do the same): 
perl -i.bak -ne 's/\s+//g;print' names
perl -i.bak -pe 's/\s+//g;' names

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T I M T O W T D I

In reply to Re: perl on the commandline by Cine
in thread perl on the commandline by Anonymous Monk

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