Sending output to logfile or STDOUT

Question

I am trying to come up with some logic to give my script an option of where to send the output.

This is a test script I started to write, I started to fizzle out trying to think of the combonations of the two options. I know I am overthinking this too much.

#!/usr/bin/perl
use strict;
use warnings;

# Modules to load
use Getopt::Long;
use Term::ANSIColor qw(:constants);

my $output = 0;

my $logfile = '';

GetOptions(

    'o' => \$output,
    'l' => \$logfile

);

if (($output == 1) && (! $logfile eq '')){



} elsif (($output == 0)($logfile eq '')){



}

If this is of any use be my guest.

Pretty much I want 3 options

0 = off 1 = stdout 2 = logfile

Where I threw a bit of a wrench at myself if when I wanted to add a custom logfile argument. I am under the impression I cannot combine the 2 arg into the same arg, can I?

The places where I will have output to write, I will control with simple if statments based on a condition, in my first interation which just allows for output to stdout. I just used the -o option and specified 0 or 1. If it was 1 it wrote the line, if it was 0 it did not.

If any has an easier solution than the one above I am open to anything.

Thanks in advance.

Answer 1

In the vein of TLP I suggest a $verbose and a $logfile option, I would also recommend that $verbose be implicitly set to true if $logfile is used. Use $verbose to control print commands as usual. The big magic is to use select to control where the print sends its output if no filehandle is given.

#!/usr/bin/perl
use strict;
use warnings;

# Modules to load
use Getopt::Long;
use Term::ANSIColor qw(:constants);

my $verbose = 0;
my $logfile;

GetOptions(

    'verbose' => \$verbose,
    'logfile=s' => \$logfile,

);

if (defined $logfile) {
  $verbose = 1;
  open my $log_handle, '>', $logfile or die "Could not open $logfile";
  # select makes print point to LOGFILE 
  select($log_handle);
}

# do stuff

print "Stuff" if $verbose;

Also since Getopt::Long gives you long options, I have changed the options names to the human readable verbose and logfile, however you can use short -v or long --verbose to your taste.

Answer 2

I would use $verbose as an option, and an optional $logfile. So, if $verbose is set, you print, if $logfile is set, you print to the log.

Then use:

if ($logfile) {
    open STDOUT, '>', $logfile or die $!;
}
print "Yada\n" if $verbose;

Or for simplicity:

sub myprint {
    return unless $verbose;
    print @_;
}
myprint("Yada\n");

Answer 3

Ok, first off, forgive me if this syntax is wrong. Its been a LONG time since I've done any perl, so take this more as a "do this sortof thing" rather than a "copy and paste my answer". With that said, I'd probably just do this:

#!/usr/bin/perl
use strict;
use warnings;

# Modules to load
use Getopt::Long;
use Term::ANSIColor qw(:constants);

my $output = 0;
my $logfile = '';

GetOptions(

    'o' => \$output,
    'l' => \$logfile

);

if (($output == 1) && (! $logfile eq '')){
    open STDOUT, $logfile
} elsif (($output == 0)($logfile eq '')){
    open STDOUT, "/dev/null"
}

... (do stuff normally here)

All I am doing is changing where STDOUT is going by either sending it to the log file or sending it to /dev/null