Question

I have Perl on Mac, Windows and Ubuntu. How can I tell from within the script which one is which?

Edit: I was asked what I am doing. It is a script, part of our cross-platform build system. The script recurses directories and figures out what files to build. Some files are platform-specific, and thus, on Linux I don’t want to build the files ending with _win.cpp, etc.

Answer 1

Examine the $^O variable which will contain the name of the operating system:

print "$^O\n"; 

Which prints linux on Linux and MSWin32 on Windows.

You can also refer to this variable by the name $OSNAME if you use the English module:

use English qw' -no_match_vars '; print "$OSNAME\n"; 

According to perlport, $^O will be darwin on Mac OS X.

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You can also use the Config core module, which can provide the same information (and a lot more):

use Config;  print "$Config{osname}\n"; print "$Config{archname}\n"; 

Which on my Ubuntu machine prints:

linux i486-linux-gnu-thread-multi 

Note that this information is based on the system that Perl was built, which is not necessarily the system Perl is currently running on (the same is true for $^O and $OSNAME); the OS won’t likely be different but some information, like the architecture name, may very well be.