Perl如何检测是从命令行运行还是从浏览器调用

Question

Is there a good way to detect if the Perl script is called from terminal/DOS or called from a web server.

I currently have this code:

sub cli {
    # return 1 if called from browser, 0 if called from command line
    if  (defined $ENV{GATEWAY_INTERFACE} ||  exists $ENV{HTTP_HOST}){
        return 0;
    }
    return 1;
}

but read that these ENV variables are not set by all servers.

The reason for this if the script run from terminal I will print text/plain formatted messages, if run from browser I will print HTML formatted messages.

Answer 1

I usually do:

if (-t STDIN) {
    //This is running from a terminal
}

Edit after reading comments : I found this other question that details a different solution : How do I check if a Perl script is running in a terminal? .

Answer 2

The following is a quick example and may not be the most accurate, but serves to demonstrate that you could check the process's parent command.

my $parent_process  = `ps -o ppid= -p $$ | xargs ps -o command= -p`;
if ($parent_process =~ /httpd/) {
   say q{CGI};
} else {
   say q{Terminal};
}

Basically, we retrieve the search for the current process, and pipe that parent process into another look up so that we can get the parent's command that was run. From the terminal it should be the shell name (eg, -bash ), but if it was run by the server, it should be the server daemon httpd (depending on the web server).

It would be much easier to have the server set an environment variable and check for the existence of that variable. This all depends on where you're running the command and who you're running the command as.

This could further be condensed into something like:

my $is_server = `ps -o ppid= -p $$ | xargs ps -o command= -p | grep httpd -q && echo "1" || echo "0"`; chomp $is_server;
if ($is_server) { ... } else { ... }