IS there an easy way to execute a shell command and capture its output...

Question

From an application? I am thinking of using fork and then waiting for the PID to finish and write the output to a file which I then read, but this seems clunky. Also there are big warnings about frameworks getting hosed if you use fork, although the "Forked" process will exec the shell command and the one that gets the PID the original process might be 'safe' from this framework corruption. I am not certain of this, it is just a guess.
If there was something like a process class where I could specify the executable and parameters, and read from it's std out until the process completed, that would be better. Or even get a callback when the process exited and an asynchronous callback for each line of data it produced.

Answer 1

That was just in response to OrangeKay implied accusation that I was some kind of hard-core Microsoft programmer that sneered at apple programmers.
You may want to book mark this, I will go over a brief history which should clear a lot of things up, about me, and about what I am doing.
Lets turn the clock back to 1998: I graduate from a university with a BS in Computer science. I had been interning at a local defense contractor writing missile testing software. This was on a proprietary hardware and so there was no "Microsoft" involved. At this point I think Bill Gates = Satan. Microsoft = Kingdom of Evil.
I get a job as a video game programmer. I write code from the Playstation, then the Playstation 2 and Gamecube. I do this for several years and again I have zero interest / knowledge of the Microsoft world beyond it being the OS which I am forced to use to play my games on. I had fought this by trying to use OS Warp and other things, but eventually since I mainly had a PC for games I had to get a windows OS, the first being NT 3.51 and then Win98 cause NT4.0 didn't support past directx 3 and everyone was using directX 5 or 6 (I do not remember).
As video game companies go, they do not last. Everyone wants to write video games, anyone with some cash wants to start a company. 1 in 1000 will make it 5 years. Needless to say, as our company began to tank, I got laid off, along with my entire team. I have cash in the bank, no big deal, right?
Well the economy started to suck, video game developers were closing down like crazy so the market was saturated with x-video game developers. 2 Years go by, no job, and almost no money. Then I get a call from some guy who wants me to come for an interview about 75 miles away. It is in a place I do not want to go. So they interview me, and ask me a bunch of general programming questions.
I leave the place, and by the time I get home there is a message on my machine asking me if I would take the job at a ridiculously high salary (I live in an area where the cost of living is very low). Well I am about out of money and its a job offer with a huge salary, so I take it.
I get there and guess what? I get to work on this "agent" that runs on windows boxes. I have NO IDEA how to program on windows. Windows is evil, why would I want to taint myself with this vile Microsoft APIs? I really have no choice, I have to learn how to develop on windows. I get to use visual studio 6, which I do not understand because I used the Borland compilers (Borland != Microsoft).
Well I start to slug through it all and get familiar with MSDN and CodeProject and CodeGuru. As the years pass, I begining applicate the examples and detailed documentation that MSDN has. I have a start page on MSDN which covers every category of operation which will take you through a tree of choices and lead you to the exact area related API calls you will need to use to do whatever you want. Now I do not think MS = Evil anymore. I switch to DevStudio 2005 which is really nice. The debugging, IDE, and everything is great.
Now the other half of this application resides on a server. That server is a Linux box, and the server app is written in Java. My stuff is still C++.
One day, I get a request, and a eMac with 10.4 PPC to make a Mac version. Now I am at the point of Mac programming as I was with Windows when I started. I didn't know anything about it. I was looking for CodeWarrior cause I used that in the past, but alas, CodeWarrior is no more. I get XCode. I see all sorts of options to make a project. BSD project, Carbon, Cocoa, etc... What the heck any of these. I can guess the BSD one is very basic, but I do not understand Carbon vs Cocoa.
So what do I do? I make a basic carbon app and make a basic Cocoa app. The carbon app looks like some kind of C++ framework. The Cocoa app? "Is this another language like Java or C#? It doesn't look like a C++ language."
Guess which choice I make. Carbon. I struggle through this looking at the docs, posting on CodeGuru and whatnot until someone finally tells me about these forums and warns me about how unfriendly people are. So I make an account and start asking questions. I eventually get my app to be multi-platform to run on windows and Mac by using some API abstractions which are easy to do since I had abstracted the Windows API by my own class wrappers.
I ask a lot of questions, very few are ever answered because I am not asking about simple things, like making windows and how to get button clicks and that stuff. I am asking stuff like, "How do you change the DNS? or How do I know when a user is about to log out?" Currently on my side list as I type this, I have 27 unresolved questions. I probably found workaround for most of them, or figured it out eventually.
On this forum mostly people are helpful when the do respond, except for OrangeKay. He definitely has a chip on his shoulder.
Over the past few years my Opinion of MS has improved greatly while my opinion of Macs (from the programmer's point of view) has dropped considerably. XCode still isn't as good as VS6 which is like 15 years old, never mind Dev studio 2005 or 2008. The documentation is scattered, not easy to find, occasionally wrong, or simply missing. The examples may not even compile or contain non-existent functions. It is unbelievable how bad it is.
If Steve Jobbs wants to really get a large coder population he ought to spend some of those billions (or is it trillions) of dollars on a team that will re-write the current documentation in a correct, easy to understand, with full examples, arranged in a logical manner for everyone to use. He should say, "See MSDN online? I want something like that, only better, it has to be MUCH better." Then he should say to the XCode team, "Look at DevStudio 2008. XCode should do EVERYTHING that does. Once that is done, IMPROVE XCode even more to make 2008 look like a joke."
To bad the Developer aspect of the "Apple Experience" has not gotten "End User" treatment. Then it would be a joy to develop on Macs.
So here I am asking for help on certain things. You wonder why I do not use Cocoa. Maybe I should, maybe I shouldn't. My first look didn't look promising, and a quick look at the docs is all about GUI's. My app has NO GUI. Again, Cocoa? Maybe it will still work, but the examples and stuff I see are all about GUIs.
When I get time, I will look at cocoa even further. MFC on windows is MOSTLY about GUI stuff, but there is a small section of it that does not deal with GUIs. CString is a great MFC class. I had to get rid of it though cause Mac's do not have a similar class. I use CStdString which is a platform agnostic CString replacement.
I hope you are all a little more enlightened. BTW my Application which runs on Mac's and PCs on no less then 3 MILLION Machines has not crashed ONCE in the past 2 years. There have been bugs, but nothing that crashed it. The bugs were mostly unforeseen situations, like what if the guy has 15 network adapters that are all LIVE? I didn't plan for that, there were complications, the server got some strange data, but it didn't crash (My app, not the server. It crashes on occasion still). Are there bugs in my code? I am sure there are, but I do not know of any, because if I did, it would be fixed.