Linux – Identify Cygwin, Linux, Windows using environment variables

detectionenvironment-variableslinuxmakefilewindows

The problem arises when makefile needs be run on different OS and various setting should be properly set up (escaping, path separator, etc) depending on OS.
The first approach was to use Windows COMSPEC:

ifneq ($(COMSPEC)$(ComSpec),)
## in windows
else 
## in linux
endif

This is false positive for Cygwin, because it sees Windows' environment variables and detects Cygwin as Windows.
Then we tried Linux PWD:

ifeq ($(PWD),)
## in windows
else 
## in linux, cygwin
endif

However, as a result of integration of off-site tool we have PWD set in windows (one of the perl's modules). So, the detection fails again.

I wonder, what is the best approach to differentiate between Cygwin, Linux, Windows using environment variables?

Best Answer

Cygwin and (tested on Ubuntu) Linux provide an $OSTYPE environment variable, set to cygwin for Cygwin and linux-gnu for (Ubuntu) Linux.

Windows does not have this variable, and so it appears to be the only one you'll need. I suppose it's possible that your Linux doesn't provide it, in which case you can use $OSTYPE to distinguish between Windows and Cygwin and then fall back to uname for Cygwin vs. Linux.

Related Solutions

Ios – How to develop for iPhone using a Windows development machine

It's certainly possible to develop on a Windows machine, in fact, my first application was exclusively developed on the old Dell Precision I had at the time :)

There are three routes;

Install OSx86 (aka iATKOS / Kalyway) on a second partition/disk and dual boot.
Run Mac OS X Server under VMWare (Mac OS X 10.7 (Lion) onwards, read the update below).
Use Delphi XE4 and the macincloud service. This is a commercial toolset, but the component and lib support is growing.

The first route requires modifying (or using a pre-modified) image of Leopard that can be installed on a regular PC. This is not as hard as you would think, although your success/effort ratio will depend upon how closely the hardware in your PC matches that in Mac hardware - e.g. if you're running a Core 2 Duo on an Intel Motherboard, with an NVidia graphics card you are laughing. If you're running an AMD machine or something without SSE3 it gets a little more involved.

If you purchase (or already own) a version of Leopard then this is a gray area since the Leopard EULA states you may only run it on an "Apple Labeled" machine. As many point out if you stick an Apple sticker on your PC you're probably covered.

The second option is more costly. The EULA for the workstation version of Leopard prevents it from being run under emulation and as a result, there's no support in VMWare for this. Leopard server, however, CAN be run under emulation and can be used for desktop purposes. Leopard server and VMWare are expensive, however.

If you're interested in option 1) I would suggest starting at Insanelymac and reading the OSx86 sections.

I do think you should consider whether the time you will invest is going to be worth the money you will save though. It was for me because I enjoy tinkering with this type of stuff and I started during the early iPhone betas, months before their App Store became available.

Alternatively, you could pick up a low-spec Mac Mini from eBay. You don't need much horsepower to run the SDK and you can always sell it on later if you decide to stop development or buy a better Mac.

Update: You cannot create a Mac OS X Client virtual machine for OS X 10.6 and earlier. Apple does not allow these Client OSes to be virtualized. With Mac OS X 10.7 (Lion) onwards, Apple has changed its licensing agreement in regards to virtualization. Source: VMWare KnowledgeBase

Bash – Setting environment variables on OS X

Bruno is right on track. I've done extensive research and if you want to set variables that are available in all GUI applications, your only option is /etc/launchd.conf.

Please note that environment.plist does not work for applications launched via Spotlight. This is documented by Steve Sexton here.

Open a terminal prompt
Type sudo vi /etc/launchd.conf (note: this file might not yet exist)

Put contents like the following into the file

# Set environment variables here so they are available globally to all apps
# (and Terminal), including those launched via Spotlight.
#
# After editing this file run the following command from the terminal to update
# environment variables globally without needing to reboot.
# NOTE: You will still need to restart the relevant application (including
# Terminal) to pick up the changes!
# grep -E "^setenv" /etc/launchd.conf | xargs -t -L 1 launchctl
#
# See http://www.digitaledgesw.com/node/31
# and http://stackoverflow.com/questions/135688/setting-environment-variables-in-os-x/
#
# Note that you must hardcode the paths below, don't use environment variables.
# You also need to surround multiple values in quotes, see MAVEN_OPTS example below.
#
setenv JAVA_VERSION 1.6
setenv JAVA_HOME /System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home
setenv GROOVY_HOME /Applications/Dev/groovy
setenv GRAILS_HOME /Applications/Dev/grails
setenv NEXUS_HOME /Applications/Dev/nexus/nexus-webapp
setenv JRUBY_HOME /Applications/Dev/jruby

setenv ANT_HOME /Applications/Dev/apache-ant
setenv ANT_OPTS -Xmx512M

setenv MAVEN_OPTS "-Xmx1024M -XX:MaxPermSize=512m"
setenv M2_HOME /Applications/Dev/apache-maven

setenv JMETER_HOME /Applications/Dev/jakarta-jmeter

Save your changes in vi and reboot your Mac. Or use the grep/xargs command which is shown in the code comment above.
Prove that your variables are working by opening a Terminal window and typing export and you should see your new variables. These will also be available in IntelliJ IDEA and other GUI applications you launch via Spotlight.

Best Answer

Related Solutions

Ios – How to develop for iPhone using a Windows development machine

Bash – Setting environment variables on OS X

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