Here's how to do that in perl without any interference from the shell:

$SIG{CHLD} = 'IGNORE';
{
    my $cpid = fork;
    defined $cpid or warn 'Could not fork: ', $! and last;
    $cpid and last;
    # child
    open STDERR, '>>', $errorfile || '/dev/null'
        or die $!;
    open STDOUT, '>', $outputfile || '/dev/null'
        or die $!;
    open STDIN, '<', $inputfile || '/dev/null'
        or die $!;
    $SIG{HUP} = sub {};
    exec "/mevs/$version/bin/mevs",
         "/mevs/$version/data/config_data/mevs2.cfg",
         'online';
    die $!;
}
# parent
[download]

That does about what nohup does. That can be further refined by imitating how a daemon starts with POSIX::setsid() to declare the child a session leader and remove itself from a controlling terminal.

Shell-like access to a background process is neither necessary or desirable in perl. We have finer weapons than that.

If you pass a single string value to system which has shell metacharacters (such as & in this case) it will use /bin/sh -c to run the command. What you're probably seeing is this shell instance's command line with the ampersand. The alternative is to use fork/exec yourself; see perldoc perlipc.

You may want to use exec in place of system, to get the backgrounding, without needing to fork and all that other work.

Update: There are times when you'd want to fork (if you needed to get the final status from when the program finished), and I have no idea what the program is that you're kicking off. But the example given doesn't attempt to capture the return value from system(), and as you're attempting to run it through nohup, in the background, I can only assume that it's not needed.

I think that I need to fork when using an exec so my perl process doesn't die. Doesn't an exec replace the current process? My perl module must run 24/7 to monitor the remote server program that also must run 24/7 and if the server program hangs, dies, or is unable to access it's database...my perl module must restart it in the background. That's the reason I was using the system call in the first place. Anyway, I am going to play around and see fi I can restruct it using a fork and exec. Thanks.