How can I detect the operating system in Perl?

Perl Problem Overview

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

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.

Perl Solutions

Solution 1 - Perl

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.

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.

Solution 2 - Perl

If you need more specific information on Windows this may help.

my $osname = $^O;


if( $osname eq 'MSWin32' ){{
  eval { require Win32; } or last;
  $osname = Win32::GetOSName();

  # work around for historical reasons
  $osname = 'WinXP' if $osname =~ /^WinXP/;
}}

Derived from sysinfo.t, which I wrote the original version.

If you need more detailed information:

my ( $osvername, $major, $minor, $id ) = Win32::GetOSVersion();

Solution 3 - Perl

Sys::Info::OS looks like a relatively clean potential solution, but currently doesn't seem to support Mac. It shouldn't be too much work to add that though.

Solution 4 - Perl

Look inside the source for File::Spec to see how it loads the right delegate based on the operating system. :)

File::Spec has a separate Perl module file for each OS. File::Spec::Win32, File::Spec::OS2, etc...

It checks the operating system and will load the appropriate .pm file at runtime based on OS.

# From the source code of File::Spec
my %module = (
      MSWin32 => 'Win32',
      os2     => 'OS2',
      VMS     => 'VMS',
      NetWare => 'Win32', # Yes, File::Spec::Win32 works on NetWare.
      symbian => 'Win32', # Yes, File::Spec::Win32 works on symbian.
      dos     => 'OS2',   # Yes, File::Spec::OS2 works on DJGPP.
      cygwin  => 'Cygwin',
      amigaos => 'AmigaOS');


my $module = $module{$^O} || 'Unix';

require "File/Spec/$module.pm";
our @ISA = ("File::Spec::$module");

Solution 5 - Perl

The variable $^O (that's a capital 'O', not a zero) holds the name of the operating system.

Depending on what you want, it may or may not give the answer you want - on my system it gives 'linux' without saying which distro. I'm not so sure about what it says on Windows or MacOS.

Solution 6 - Perl

Here's a quick reference on how to find the OS the local machine is running from Perl.

> The $^O variable ($OSTYPE if you use English) contains the operating system that your perl binary was built for.

Solution 7 - Perl

A classic one-liner:

my $windows=($^O=~/Win/)?1:0;# Are we running on windows?

Solution 8 - Perl

FYI on Mac computers $^O now returns 'darwin' for 10.13.6 (High Sierra) and 10.15.4 (Catalina).

Solution 9 - Perl

#Assign the $home_directory variable the path of the user's home directory
my $home_directory = ($^O eq /Win/) ? $ENV{HOMEPATH} : $ENV{HOME};
#Then you can read/write to files in the home directory
open(FILE, ">$home_directory/my_tmp_file");
print FILE "This is a test\n";
close FILE;
#And/or read the contents of the file
open(FILE, "<$home_directory/my_tmp_file");
while (<FILE>){
	print $_;
}
close FILE;

Solution 10 - Perl

For a generic mapping in a pre-packaged perl module, check out Perl::OSType.

It's used by Module::Build.

Solution 11 - Perl

yes using Config module can be a good thing. One more possibility is getting the info from /etc/*release files

for eg..

cat /etc/os-release

NAME="UBUNTU"
VERSION="12.0.2 LTS, Precise Pangolin"
ID="UBUNTU"
ID_LIKE=debian
PRETTY_NAME="Ubuntu precise (12.0.2 LTS)"
VERSION_ID="12.04"

Content Type	Original Author	Original Content on Stackoverflow
Question	mxcl	View Question on Stackoverflow
Solution 1 - Perl	Robert Gamble	View Answer on Stackoverflow
Solution 2 - Perl	Brad Gilbert	View Answer on Stackoverflow
Solution 3 - Perl	Leon Timmermans	View Answer on Stackoverflow
Solution 4 - Perl	brian d foy	View Answer on Stackoverflow
Solution 5 - Perl	Geoglyph	View Answer on Stackoverflow
Solution 6 - Perl	willasaywhat	View Answer on Stackoverflow
Solution 7 - Perl	Hawk	View Answer on Stackoverflow
Solution 8 - Perl	Amer Neely	View Answer on Stackoverflow
Solution 9 - Perl	bcarroll	View Answer on Stackoverflow
Solution 10 - Perl	Randall	View Answer on Stackoverflow
Solution 11 - Perl	GC 13	View Answer on Stackoverflow