Can I charge money for software that I write for Linux?

[Onceler]

Or does it all have to be free?

 

[lxskllr]

That's not a problem. If you were restricted from sale, it would be non-free software. You can write 100% proprietary software for GNU/Linux, and charge money as you see fit, but proprietary software is lame.

 

[SammichPG]

Or does it all have to be free?

Depending on the libraries and compiler license used you could distribute a completely closed source program.

Most linux program are free as in free beer, but it's not mandatory.
The whole open source movement is about having the freedom to look at the source code, not about providing software free of charge (Stallman used to sell his programs for example).

https://en.wikipedia.org/wiki/Business_models_for_open-source_software

Good luck supporting a closed source program across the major distros though.

 

[Red Squirrel]

I think you can but if you use any 3rd party libraries you will have to abide by their rules, I believe.

Personally I'd make it free and just charge for support.

 

[Mark R]

I think you can but if you use any 3rd party libraries you will have to abide by their rules, I believe.

Personally I'd make it free and just charge for support.

True.

However, most library providers will have much weaker rules if you do not static-link to the library (you only dynamic link to an unmodified version of the library). This is the case for GPL licensed libraries - if you static link to the library, your software MUST be GPL licensed. If you dynamic link, then there are no restrictions on your software.

 

[JManInPhoenix]

Even if your apps are great, you would probably have few or no takers on purchasing your products for Linux. I have been running Ubuntu for about 7 years now - whenever I need an app/program, I always check the usual sources for free versions. If you need something for Linux, chances are someone has already wrote it and distributed it for free.

 

[powerhouse65]

1. Of course you can take money for your apps - just make sure you meet the license requirements of some open-source tools you may need.
2. Selling apps for Linux requires you to think twice on what you are trying to sell. Example: Under Windows you could sell any stupid utility application, for example a defrag utility. Windows got a big market, and comes with next to nothing (well, it has defrag, but Windows users are used to replace the freebies for paid software, just scare them a little). Under Linux you would have a much smaller market and next to no chance selling such utilities.
3. I can see 3 potential market segments for Linux:
I. Games that look like those running on Windows. But also check out Steam to know what you are up to.
II. Professional software for certain markets: Most likely you need Windows compatibility, at least for exchanging data. I could imagine the possibility to run software for physicians or dentists or the like on Linux, or even ERP. Just make sure it interfaces.
III. Software and/or services for data centers/servers/computing: I think Linux is much more popular in professional IT circles. Enterprises are used to pay both for software and for services.

Whatever you do - good luck!