I was puzzled when my script gave me different behaviour when I attached an F to the switches:
[jmccrea@juno jmccrea]$ cat testy2

#!perl -ap
split;

[jmccrea@juno jmccrea]$ perl -MO=Deparse testy2

LINE: while (defined($_ = <ARGV>)) {
    @F = split(/\s+/, $_, 0);
    split(/\s+/, $_, 0);
}
continue {
    print $_;
}
testy2 syntax OK

[jmccrea@juno jmccrea]$ cat testy 

#!perl -apF
split;

[jmccrea@juno jmccrea]$ perl -MO=Deparse testy 

LINE: while (defined($_ = <ARGV>)) {
    @F = split(/\n/, $_, 0);
    split(/\s+/, $_, 0);
}
continue {
    print $_;
}
testy syntax OK

[download]
So with the F, the autosplit splits on /\n/, otherwise on /\s+/. Having thought about it, it appears that the next character after the F is interpreted as the pattern on which to split, that character being a carriage return. It just seems very odd that it wouldn't grab the empty string instead. Can't find anything in the docs.

Jasper

In reply to autosplit behaviour with and without F by Jasper

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