Short PyObjC script to get a Mac's serial number without calling `system_profiler`.

get_serial.py

#!/usr/bin/python
# (Note that we must use system Python on a Mac.)

####
# Quick script to get the computer's serial number.
#
# Written for @john.e.lamb on the MacAdmins Slack team.

import objc
import CoreFoundation

def import_iokit_functions_and_variables():
    iokit = objc.initFrameworkWrapper(
        "IOKit",
        frameworkIdentifier="com.apple.framework.IOKit",
        frameworkPath=objc.pathForFramework("/System/Library/Frameworks/IOKit.framework"),
        globals=globals()
        )
    functions = [
    	("IOServiceGetMatchingService", b"II@"),
    	("IOServiceMatching", b"@or*", "", dict(
    		arguments=
    		{
    			0: dict(
                    type=objc._C_PTR + objc._C_CHAR_AS_TEXT,
                    c_array_delimited_by_null=True,
                    type_modifier=objc._C_IN)
    		}
    		)),
    	("IORegistryEntryCreateCFProperty", b"@I@@I")
    	]
    variables = [
    	("kIOMasterPortDefault", b"I"),
    	("kIOPlatformSerialNumberKey", b"*")
    	]
    objc.loadBundleFunctions(iokit, globals(), functions)
    objc.loadBundleVariables(iokit, globals(), variables)

def get_serial():
    import_iokit_functions_and_variables()
    platformExpert = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"))
    serial = IORegistryEntryCreateCFProperty(platformExpert, CoreFoundation.CFSTR(kIOPlatformSerialNumberKey), CoreFoundation.kCFAllocatorDefault, 0)
    return serial

if __name__ == '__main__':
    serial = get_serial()
    print("Serial: {}".format(serial))