in reply to Re^5: Perl & R ?
in thread Perl & R ?

thank you. this does work!

what does /dev/null stand for?

what does 2 and &1 stand for

how to interpret this command

I am new to perl. I am sorry if these questions sound trivial

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Re^7: Perl & R ?
by polettix (Vicar) on Mar 29, 2005 at 09:53 UTC
    This is not Perl, this is shell. When you call the system function, you pass a string that is executed by a shell (usually /bin/sh) just like you called
    /bin/sh -c your-command-here
    /dev/null is a special device that acts like a well for your data - it silently eats them and throws them into nowhere. Useful for problems, ain't it? :)

    2>&1 redirects standard error (file descriptor 2, where error messages usually are written) to standard output (file descriptor 1, where normal messages are usually printed). I don't know what the Anonymous Monk wanted to do, but I bet that he should change the order of redirections:

    ... >/dev/null 2>&1
    Otherwise, you'll have errors on the standard output, and the normal standard output thrown away (while I think that he inteded to throw away both of them).

    You can learn a bunch of things about the shell viewing the bash man page, anyway.

    Flavio

    Don't fool yourself.