more on identifying the system a program is running on...

[Fred Smith]

I asked recently about using /etc/redhat-release and got some useful answers.
My thanks to all who replied.

Now a slight variant:

Can anyone suggest some resource that a PROGRAM (compiled C program) can
examine while running to find out what platform it is runninng on ?

Things that come to mind include:
1. output of uname to see if the kernel version contains "elX" where X
is a digit, such as el4, el5, etc., identifying RHEL-4, RHEL-5, etc.
2. do the same thing by exmining the filename of the kernel (if I knew
   how to find the file for the currently running kernel, that is.

can anyone suggest any other checks I could do?

Thanks again!

[Frank Murphy]

On 01/07/10 14:49, fred smith wrote:
> Can anyone suggest some resource that a PROGRAM (compiled C program) can
> examine while running to find out what platform it is runninng on ?

cd /proc | cat version

[Patrick O'Callaghan]

On Thu, 2010-07-01 at 14:55 +0100, Frank Murphy wrote:
> On 01/07/10 14:49, fred smith wrote:
> > Can anyone suggest some resource that a PROGRAM (compiled C program) can
> > examine while running to find out what platform it is runninng on ?
>
> cd /proc | cat version

Huh?

poc

[JD]

On 07/01/2010 06:55 AM, Frank Murphy wrote:
> cd /proc | cat version

$ cd /proc | cat version
cat: version: No such file or directory
$ ls /proc/version
/proc/version
$ cat /proc/version
Linux version 2.6.34-git16.fc13.i686 ([e-mail]) (gcc 
version 4.4.4 20100503 (Red Hat 4.4.4-2) (GCC) ) #3 PREEMPT Sun May 30 
21:17:11 PDT 2010

[Frank Murphy]

On 01/07/10 16:56, JD wrote:
> On 07/01/2010 06:55 AM, Frank Murphy wrote:
> > cd /proc | cat version
>
> $ cd /proc | cat version
> cat: version: No such file or directory
> $ ls /proc/version
> /proc/version
> $ cat /proc/version
> Linux version 2.6.34-git16.fc13.i686 ([e-mail]) (gcc
> version 4.4.4 20100503 (Red Hat 4.4.4-2) (GCC) ) #3 PREEMPT Sun May 30
> 21:17:11 PDT 2010

My mistake:
$ cd /proc |cat version
Linux version 2.6.33.5-124.fc13.i686.PAE 
([e-mail]) (gcc version 4.4.4 20100503 
(Red Hat 4.4.4-2) (GCC) ) #1 SMP Fri Jun 11 09:42:24 UTC 2010

[Patrick O'Callaghan]

On Thu, 2010-07-01 at 17:02 +0100, Frank Murphy wrote:
> My mistake:
> $ cd /proc |cat version

Or just 'cat proc/version'

poc

[g]

Patrick O'Callaghan wrote:
> On Thu, 2010-07-01 at 17:02 +0100, Frank Murphy wrote:
> > My mistake:
> > $ cd /proc |cat version
>
> Or just 'cat proc/version'

better yet 'cat /proc/version'.

[Patrick O'Callaghan]

On Thu, 2010-07-01 at 17:20 +0000, g wrote:
> Patrick O'Callaghan wrote:
> > On Thu, 2010-07-01 at 17:02 +0100, Frank Murphy wrote:
> > > My mistake:
> > > $ cd /proc |cat version
> >
> > Or just 'cat proc/version'
>
> better yet 'cat /proc/version'.

Of course.

poc

[Tim]

On Thu, 2010-07-01 at 17:02 +0100, Frank Murphy wrote:
> My mistake:
> $ cd /proc |cat version
> Linux version 2.6.33.5-124.fc13.i686.PAE 
> ([e-mail]) (gcc version 4.4.4 20100503 
> (Red Hat 4.4.4-2) (GCC) ) #1 SMP Fri Jun 11 09:42:24 UTC 2010

I still don't see how you're getting that to work.  If you had ; instead
of | between the commands, then I could see it working.

$ cd /proc ;cat version
Linux version 2.6.27.25-78.2.56.fc9.i686 (mockbuild@) (gcc version 4.3.0
20080428 (Red Hat 4.3.0-8) (GCC) ) #1 SMP Thu Jun 18 12:47:50 EDT 2009

But it still seems like far more messing around than's needed.  If you
want to read that file, simply do so.

i.e. cat /proc/version

I see no point in changing the current working directory to /proc.

[Bruno Wolff III]

On Thu, Jul 01, 2010 at 09:49:49 -0400,
  fred smith  wrote:
> Can anyone suggest some resource that a PROGRAM (compiled C program) can
> examine while running to find out what platform it is runninng on ?

You could look at the source for uname and see what it does.
> can anyone suggest any other checks I could do?

What are you really trying to do? Normally you want to check to see if some
feature is supported or an ABI versiob, not really a program version.
Sometimes a program version makes a good proxy for those. It's hard to suggest
something without knowing your higher level goal.

[Jerry Feldman]

On 07/01/2010 09:49 AM, fred smith wrote:
> I asked recently about using /etc/redhat-release and got some useful answers.
> My thanks to all who replied.
>
> Now a slight variant:
>
> Can anyone suggest some resource that a PROGRAM (compiled C program) can
> examine while running to find out what platform it is runninng on ?
>
> Things that come to mind include:
> output of uname to see if the kernel version contains "elX" where X
>
> is a digit, such as el4, el5, etc., identifying RHEL-4, RHEL-5, etc.
> 2. do the same thing by exmining the filename of the kernel (if I knew
>    how to find the file for the currently running kernel, that is.

(1) There is a uname(2) system call that any C or C++ program can call
that has all the information that the uname(1) command provides. Do a
'man 2 uname' for details.

(2) I'm not exactly sure how to get at the physical kernel file without
first doing a uname, then matching that information with
/boot/vmlinux-xxxx. /proc/versions can tell you more information, but
not exactly the file name.