in reply to Does Perl 5 (or 6?) need another built-in variable for the -F switch?

If it is a one-liner then your perl is probably simple enough to go into " rather than ' (just backlash any $vars or double quotes), so: 
export F="\t"
perl -F$F -line "munge(@F); print join($F, @F);" file

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The join($F, @F) looks a bit evil, but hey.

Sadly, this doesn't work: 

F="\t" perl -F$F -line "munge(@F); print join($F, @F);" file

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Presumably because the prefixed env var doesn't apply to the shell's expansion of the line.

Does anyone know a trick to make this (shorter) approach work?

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Re^2: Does Perl 5 (or 6?) need another built-in variable for the -F switch?
by Anonymous Monk on Nov 03, 2006 at 09:43 UTC
    You didn't try that, did you? It's not going to work. See, if $F is interpolated by the shell, you end up with: 
        join(t, @F)

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    This is wrong on several accounts. First, inside the one-liner, you need to place quotes around $F, otherwise, at best you end up with bare words, but more likely, you end up with something that cannot be compiled (Try F=":") for instance. Second, the shell doesn't know "\t" as something special. It just sees an escaped t, and hence, F="\t" is equivalent to "t".

    Also, the command line switches -line won't do what you expect it to do. It means "chomp of newlines, and add newlines to print, and modify the input file, leaving a backup with extension 'ne'".

    You probably want (untested): 

        F='  '  # Enter a tab here.
    perl -F"$F" -i -wlne "munge(@F); print join('$F',@F);" file

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    But you can to better, it can also work if you want to use single quotes for the one liner. The shell's quoting mechanism are superior to Perls in some expects. Exploit them: 

       perl -F"$F" -i -wlpe 'munge(@F); $_ = join("'$F'",@F);'

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      I tried it with a : seperator, but you're right I didn't use the \t. Mea culpa.
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        Odd. Using \t *does* work (in the sense that it compiles) because join(t, @F) is valid Perl, and all it does is generate a warning. Using : however does not work, unless your Perl can compile join(:, @F).
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