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printing to STDOUT and a Logfile

by oroburos (Initiate)
on Oct 29, 2002 at 00:34 UTC ( #208643=perlquestion: print w/ replies, xml ) Need Help??
oroburos has asked for the wisdom of the Perl Monks concerning the following question:

Monks: How can I print to STDOUT and a logfile at the same time? I am trying to capture the results of an installation script. Of course I need to display the contents to STDOUT but I really do not want to create two print statements if it is not necessary, Thanks for any assistance Mike

Comment on printing to STDOUT and a Logfile
Re: printing to STDOUT and a Logfile
by rbc (Curate) on Oct 29, 2002 at 00:39 UTC
    This is the way I do it. It my be too simple for all your logging needs.
    perl -e 'print "Hello\n";' | tee logfile
    ... or If I also want to trap STDERR I do ...
    perl -e 'print "Hello\n;' >& logfile
    ... but then again does logging need to be complicated?
Re: printing to STDOUT and a Logfile
by Ovid (Cardinal) on Oct 29, 2002 at 00:42 UTC

    If you're on a Unix-like system, you can check out the 'tee' command:

    
    $ man tee
    
    NAME
           tee  - read from standard input and write to standard out-
           put and files
    

    Another option, which I have never used, is Tie::FileHandle::MultiPlex.

    Update: One way that I have used 'tee' in the past.

    use constant TEE => '| tee '; use constant TO_PRINTER => "| lp -d lex_text"; my $file = REPORT_DIR . "cc_auth_$DATETIME"; open CCAUTH_REPORT, TEE . $file . TO_PRINTER or die $!;

    Cheers,
    Ovid

    Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.

      Another option, which I have never used, is Tie::FileHandle::MultiPlex.

      ... and if you hunt around CPAN, you'll also find Filter::tee and IO::Tee, which look to be of a similar vein.

      Update: D'oh... shoulda tested the code in the <readmore> before posting. Although it prolly still could be made to work, ybiC's code is simpler.

          --k.


Re: printing to STDOUT and a Logfile
by jsprat (Curate) on Oct 29, 2002 at 01:15 UTC
    You could always use IO::Tee. For example,

    #!/usr/bin/perl use strict; use warnings; use IO::Tee; open my $log, '>stdout.log' or warn "Can't write logfile: $!"; my $tee = new IO::Tee(\*STDOUT, $log); # Use it like a file handle print $tee "Just another perl hacker,\n"; # Use the print method of the IO::Tee object $tee->print("Just another perl monk.\n"); $tee->flush; __END__ Output: C:\S\Test>iotee.pl Just another perl hacker, Just another perl monk. C:\S\Test>type stdout.log Just another perl hacker, Just another perl monk.

    Hope it's helpful,

    Update: simplified the example

Re: printing to STDOUT and a Logfile (cross-platform sub)
by ybiC (Prior) on Oct 29, 2002 at 01:22 UTC

    Here's one cross-platform way to simultaneously print to STDOUT and a filehandle.

    # print messages to both console and logfile sub PrintLogCon { print @_; print(LOG @_) or die "Error printing to $logfile: $!"; }

    and you'd call it thusly:

    use warnings; use strict; open(LOG, ">$logfile") or die "Error opening $logfile: $!"; ... ... ... do->stuff; do->it(again) or PrintLogCon("Error: $!"); do->stuff(more); ... ... ... close LOG or die "Error closing $logfile: $!"; __END__
    Phat props to mad monk Petruchio for showing me this a while back.
        cheers,
        Don
        striving toward Perl Adept
        (it's pronounced "why-bick")

    Update2: consistant-ized scalar for logfile
    Update1: or use IO::Tee as shown by fine monk jsprat.

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