Is there a limit to os.popen()?

[Carl J. Van Arsdall]

I'm not sure the proper way to phrase the question, but let me try.

Basically, I'm working with a script where someone wrote:

kr = string.strip(os.popen('make kernelrelease').read())
And then searches kr to match a regular expression.

This seems to have been working, however lately when this line executes
I get a number of messages to stderr after several minutes of execution:

cat: write error: Broken pipe
cat: write error: Broken pipe
cat: write error: Broken pipe
I know the output from this make has been growing (make applies some
patches and the patch list is growing). Does os.popen() have some kind
of read buffer limit that i'm hitting which is causing things to break?


--

Carl J. Van Arsdall
cv*********@mvista.com
Build and Release
MontaVista Software

[cdecarlo]

Hello,

I'm not 100% sure on this but to me it looks like there is a problem in
your make file. I would look in there first, see where 'cat' is
executed, I bet your problem will be around there.

Hope this helps,

Colin

Carl J. Van Arsdall wrote:

I'm not sure the proper way to phrase the question, but let me try.

Basically, I'm working with a script where someone wrote:

kr = string.strip(os.popen('make kernelrelease').read())
And then searches kr to match a regular expression.

This seems to have been working, however lately when this line executes
I get a number of messages to stderr after several minutes of execution:

cat: write error: Broken pipe
cat: write error: Broken pipe
cat: write error: Broken pipe
I know the output from this make has been growing (make applies some
patches and the patch list is growing). Does os.popen() have some kind
of read buffer limit that i'm hitting which is causing things to break?


--

Carl J. Van Arsdall
cv*********@mvista.com
Build and Release
MontaVista Software

[Carl J. Van Arsdall]

cdecarlo wrote:

Hello,

I'm not 100% sure on this but to me it looks like there is a problem in
your make file. I would look in there first, see where 'cat' is
executed, I bet your problem will be around there.

Hope this helps,

Colin

Well, running the make on the command line seems to work just fine, no
errors at all. I, in fact, get the results I expect with no error
messages printed out. I thought maybe something might have used cat as
a utility, thanks, i'll keep on it.

-c

--

Carl J. Van Arsdall
cv*********@mvista.com
Build and Release
MontaVista Software

[sreekant]

kr = string.strip(os.popen('make kernelrelease').read())

If make is being executed, I presume that the python script has rw
access to the location. How about

x=os.system("make kernelrelease my_report 2>&1 ")
kr=open("my_report").read()
Just a blind throw.

Good luck
sree

[Lawrence D'Oliveiro]

In article <ma***************************************@python. org>,
"Carl J. Van Arsdall" <cv*********@mvista.comwrote:

>Well, running the make on the command line seems to work just fine, no
errors at all.

What about running it as

make kernelrelease | cat

This way the output goes to a pipe, which is what happens when it's
called from your script. Do you see those "broken pipe" messages after a
few minutes in this case?

[Carl J. Van Arsdall]

Lawrence D'Oliveiro wrote:

In article <ma***************************************@python. org>,
"Carl J. Van Arsdall" <cv*********@mvista.comwrote:

>Well, running the make on the command line seems to work just fine, no
errors at all.

What about running it as

make kernelrelease | cat

This way the output goes to a pipe, which is what happens when it's
called from your script. Do you see those "broken pipe" messages after a
few minutes in this case?

Alright, so I tried that line in the interpreter and got the same
problem. So let me quickly state what I know, and what I'm starting to
infer.

Anyhow, running make on the command line gives me no problems. There
are cats all over the makefile, I checked, but I don't seem to have any
problems on the command line. Now, when attempting to run this make in
python things seem to go alright, except I get tons of errors dumped to
the screen, its very confusing. I don't know too much about pipes
though or how exactly to go about debugging this. Could it be something
like, make's output is piped correctly but pipes used by cat within the
makefile get screwed up inside python somehow?

-c


--

Carl J. Van Arsdall
cv*********@mvista.com
Build and Release
MontaVista Software

[Lawrence D'Oliveiro]

In article <ma***************************************@python. org>,
"Carl J. Van Arsdall" <cv*********@mvista.comwrote:

>Lawrence D'Oliveiro wrote:

>In article <ma***************************************@python. org>,
"Carl J. Van Arsdall" <cv*********@mvista.comwrote:

>>Well, running the make on the command line seems to work just fine, no
errors at all.

What about running it as

make kernelrelease | cat

This way the output goes to a pipe, which is what happens when it's
called from your script. Do you see those "broken pipe" messages after a
few minutes in this case?

Alright, so I tried that line in the interpreter and got the same
problem.

No, I wanted you to try it from a bash command prompt, to try to
simulate the environment when the make command on its own is invoked via
popen.