gistfile1.c

#include <CoreFoundation/CoreFoundation.h>

void xcselect_trigger_install_request(const char *str) {
	CFMutableDictionaryRef 	options;
	CFStringRef				toolNameKey, toolName;
	CFDataRef				optionsData;

	options = CFDictionaryCreateMutable(NULL, 0, NULL, NULL);
	toolNameKey = CFStringCreateWithCString(NULL, "tool-name", kCFStringEncodingMacRoman);
	toolName = CFStringCreateWithCString(NULL, str, kCFStringEncodingMacRoman);
	CFDictionarySetValue(options, toolNameKey, toolName);
	optionsData = CFPropertyListCreateData(NULL, (CFPropertyListRef)options, kCFPropertyListBinaryFormat_v1_0, 0, NULL);

	CFRelease(toolNameKey);
	CFRelease(toolName);
	CFRelease(options);

	if(optionsData) {
		CFStringRef 		portName;
		CFMessagePortRef 	port;
		CFDataRef 			returnData;

		portName  = CFStringCreateWithCString(NULL, "com.apple.dt.CommandLineTools.installondemand", kCFStringEncodingMacRoman);
		port = CFMessagePortCreateRemote(NULL, portName);

		if(port) {
			CFMessagePortSendRequest(port, 0, optionsData, 0, 0, NULL, &returnData);
		}
	}
}

int main(int argc, const char **argv) {
	const char *name = "clinstall";
	if(argc > 1)
		name = argv[1];

	xcselect_trigger_install_request(name);
	return 0;
}