commands.getstatusoutput result is not command line exit value!!!
I'm running a command like
import commands
result = commands.getstatusoutput('somecommand')
print result[0]
3072
However, this exit code made no sense so I ran it manually from the
command line in bash on my linux server and it gives the exit code as
12, not this weird 3072 number.
So I tried os.system('somecommand') in the interactive python shell and
it too returned the same result for the exit code as the unix shell, 12,
but re-running the commands.getstatusoutput() with the exact same
command still gave 3072.
Is commands.getstatusoutput() broken or something?
-h
--
Hari Sekhon
--
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Re: commands.getstatusoutput result is not command line exit value!!!
Hari Sekhon wrote:
I'm running a command like
import commands
result = commands.getstatusoutput('somecommand')
print result[0]
3072
However, this exit code made no sense so I ran it manually from the
command line in bash on my linux server and it gives the exit code as
12, not this weird 3072 number.
So I tried os.system('somecommand') in the interactive python shell and
it too returned the same result for the exit code as the unix shell, 12,
but re-running the commands.getstatusoutput() with the exact same
command still gave 3072.
Is commands.getstatusoutput() broken or something?
-h
No, it's just returning the error code in the top half of a sixteen-bit
value. You will notice that 3072 == 2 * 256.
That's always been the way the Unix return code has been returned
programattically, but the shell shifts it down to make it more usab;e.
regards
Steve
--
Steve Holden +44 150 684 7255 +1 800 494 3119
Holden Web LLC/Ltd http://www.holdenweb.com
Skype: holdenweb http://holdenweb.blogspot.com
Recent Ramblings http://del.icio.us/steve.holden
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Re: commands.getstatusoutput result is not command line exit value!!!
I don't quite understand what you are saying here:
2 * 256 is 512,
2 ** 256 is some extremely large number.
2**12 is 4096.
So how does 3072 factor into this?
Could you explain what you mean by "the error in the top half of a
sixteen-bit value"?
This makes no sense to me at this moment.
-h
Hari Sekhon
Steve Holden wrote:
Hari Sekhon wrote:
I'm running a command like
import commands
result = commands.getstatusoutput('somecommand')
print result[0]
3072
However, this exit code made no sense so I ran it manually from the
command line in bash on my linux server and it gives the exit code as
12, not this weird 3072 number.
So I tried os.system('somecommand') in the interactive python shell and
it too returned the same result for the exit code as the unix shell, 12,
but re-running the commands.getstatusoutput() with the exact same
command still gave 3072.
Is commands.getstatusoutput() broken or something?
-h
No, it's just returning the error code in the top half of a sixteen-bit
value. You will notice that 3072 == 2 * 256.
That's always been the way the Unix return code has been returned
programattically, but the shell shifts it down to make it more usab;e.
regards
Steve
--
http://mail.python.org/mailman/listinfo/python-list
Re: *** Spam *** Re: commands.getstatusoutput result is not command line exit value!!!
A famous Holden typo - it should have been 12 * 256 == 3072, but
really it shouldn't have been beyond you to perform a division of 3072
by 12 (given that you already knew the number 12 was potentially involved).
Basically the value you want is shifted up 8 bits. Perhaps I should more
understandably have said:
12 8 == 3072
regards
Steve
Hari Sekhon wrote:
I don't quite understand what you are saying here:
2 * 256 is 512,
2 ** 256 is some extremely large number.
2**12 is 4096.
So how does 3072 factor into this?
Could you explain what you mean by the error in the top half of a
sixteen-bit value?
This makes no sense to me at this moment.
-h
Hari Sekhon
Steve Holden wrote:
Hari Sekhon wrote:
I'm running a command like
import commands
result = commands.getstatusoutput('somecommand')
print result[0]
3072
However, this exit code made no sense so I ran it manually from the
command line in bash on my linux server and it gives the exit code as
12, not this weird 3072 number.
So I tried os.system('somecommand') in the interactive python shell and
it too returned the same result for the exit code as the unix shell, 12,
but re-running the commands.getstatusoutput() with the exact same
command still gave 3072.
Is commands.getstatusoutput() broken or something?
-h
No, it's just returning the error code in the top half of a sixteen-bit
value. You will notice that 3072 == 2 * 256.
That's always been the way the Unix return code has been returned
programattically, but the shell shifts it down to make it more usab;e.
regards
Steve
--
Steve Holden +44 150 684 7255 +1 800 494 3119
Holden Web LLC/Ltd http://www.holdenweb.com
Skype: holdenweb http://holdenweb.blogspot.com
Recent Ramblings http://del.icio.us/steve.holden
--
http://mail.python.org/mailman/listinfo/python-list
Re: commands.getstatusoutput result is not command line exit value!!!
I'm sorry, this may seem dense to you but I have to ask. What on earth
are you talking about?
Why is it shifted 8 bits to the left? Why is there bitshifting at all?
Why doesn't commands give the same exit value as os.system() and the
unix cli?
When you choose to exit a program you give it a return value to exit
with, so why would this change, I exit with the number 1 then expect
that number to be the exit code, right? Where do these higher numbers
come into the equation and why?
Please assume that I am not a mind reader and require explanation before
I can understand.
Perhaps you aren't a mind reader either and don't know why the writers
of the commands lib chose to do this insanity either? It seems the
os.system() guys did the right thing, I wonder why
commands.getstatusoutput doesn't...
Having just tested it manually with a shell script returning 2,
commands.getstatusoutput did give the exit code as 512, so it does seem
to generically shift the exit code 8 bits to the left or multiply it by
256 for those of us who need some more straight talking...
ugg, perhaps it's time to stop using this thing and use a better lib module.
any explanations welcome...
-h
Hari Sekhon
Steve Holden wrote:
A famous Holden typo - it should have been 12 * 256 == 3072, but
really it shouldn't have been beyond you to perform a division of 3072
by 12 (given that you already knew the number 12 was potentially
involved).
Basically the value you want is shifted up 8 bits. Perhaps I should
more understandably have said:
12 8 == 3072
regards
Steve
Hari Sekhon wrote:
I don't quite understand what you are saying here:
2 * 256 is 512,
2 ** 256 is some extremely large number.
2**12 is 4096.
So how does 3072 factor into this?
Could you explain what you mean by the error in the top half of a
sixteen-bit value?
This makes no sense to me at this moment.
-h
Hari Sekhon
Steve Holden wrote:
Hari Sekhon wrote:
I'm running a command like
import commands
result = commands.getstatusoutput('somecommand')
print result[0]
3072
However, this exit code made no sense so I ran it manually from the
command line in bash on my linux server and it gives the exit code
as 12, not this weird 3072 number.
So I tried os.system('somecommand') in the interactive python shell
and it too returned the same result for the exit code as the unix
shell, 12, but re-running the commands.getstatusoutput() with the
exact same command still gave 3072.
Is commands.getstatusoutput() broken or something?
-h
No, it's just returning the error code in the top half of a
sixteen-bit value. You will notice that 3072 == 2 * 256.
That's always been the way the Unix return code has been returned
programattically, but the shell shifts it down to make it more usab;e.
regards
Steve
--
http://mail.python.org/mailman/listinfo/python-list
Re: commands.getstatusoutput result is not command line exit value!!!
Hari Sekhon wrote: I'm sorry, this may seem dense to you but I have to ask. What on earth are you talking about? Why is it shifted 8 bits to the left? Why is there bitshifting at all? Why doesn't commands give the same exit value as os.system() and the unix cli? because that's how Unix's wait() operation returns the status code (as mentioned in the commands section of the library reference). you can use the os.WIFEXITED(status) and os.WEXITSTATUS(code) helpers to convert between wait return codes and signal numbers/exit codes. see: http://docs.python.org/lib/os-process.html or you can forget about the obsolete commands module, and use the new subprocess module instead; e.g. def getstatusoutput(command): from subprocess import Popen, PIPE, STDOUT p = Popen(command, stdout=PIPE, stderr=STDOUT, shell=True) s = p.stdout.read() return p.wait(), s print getstatusoutput(ls -l /bin/ls) (0, '-rwxr-xr-x1 root root68660 Aug 12 2003 /bin/ls\n') the subprocess module is highly flexible; see the library reference for details. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: commands.getstatusoutput result is not command line exit value!!!
Hari Sekhon schrieb: I'm sorry, this may seem dense to you but I have to ask. What on earth are you talking about? You may not be dense, but you are certainly fairly aggressive in your postings. If you just want to complain, go ahead. If you want actual help, you should reconsider your tone. Why is it shifted 8 bits to the left? As Steve says, that what the system returns (from popen(3)), in this case. It's the true exit status, not just the exit code. Why is there bitshifting at all? Read some Unix book. Why doesn't commands give the same exit value as os.system() and the unix cli? Read some Unix book. When you choose to exit a program you give it a return value to exit with, so why would this change, I exit with the number 1 then expect that number to be the exit code, right? Read some Unix book. Hint: how do you know whether the program was killed, and didn't actually invoke exit(3)? Where do these higher numbers come into the equation and why? Read some Unix book. Hint: Read about WIFEXITED, WIFSIGNALED, and WEXITSTATUS. Please assume that I am not a mind reader and require explanation before I can understand. You are apparently not a documentation reader, as well. Nobody owes you an explanation. Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
Re: commands.getstatusoutput result is not command line exit value!!!
ok, I was thinking of shifting using subprocess, guess I'd better do
that and forget about this waste of time.
thanks
Hari Sekhon
Fredrik Lundh wrote:
Hari Sekhon wrote:
I'm sorry, this may seem dense to you but I have to ask. What on earth
are you talking about?
Why is it shifted 8 bits to the left? Why is there bitshifting at all?
Why doesn't commands give the same exit value as os.system() and the
unix cli?
because that's how Unix's wait() operation returns the status code (as
mentioned in the "commands" section of the library reference).
you can use the os.WIFEXITED(status) and os.WEXITSTATUS(code) helpers to
convert between wait return codes and signal numbers/exit codes. see:
http://docs.python.org/lib/os-process.html
or you can forget about the obsolete "commands" module, and use the new
subprocess module instead; e.g.
def getstatusoutput(command):
from subprocess import Popen, PIPE, STDOUT
p = Popen(command, stdout=PIPE, stderr=STDOUT, shell=True)
s = p.stdout.read()
return p.wait(), s
print getstatusoutput("ls -l /bin/ls")
(0, '-rwxr-xr-x1 root root68660 Aug 12 2003 /bin/ls\n')
the subprocess module is highly flexible; see the library reference for
details.
/F
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Re: commands.getstatusoutput result is not command line exit value!!!
Steve Holden wrote:
Hari Sekhon wrote:
I'm running a command like
import commands
result = commands.getstatusoutput('somecommand')
print result[0]
3072
...
No, it's just returning the error code in the top half of a sixteen-bit
value. You will notice that 3072 == 2 * 256.
For the rest of us playing along at home, there is a typo there:
The preceding line should read:
value. You will notice that 3072 == 12 * 256.
--Scott David Daniels
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
Re: commands.getstatusoutput result is not command line exit value!!!
yes already noted by Steve, thanks.
I should have spotted that myself straight away but I was too wrapped
up in this whole "I didn't realise there were 2 sets of numbers" thing,
gotta go read some unix programming books it would seem this is a os
function that I am not aware of.
I still reserve the right to be annoyed at commands for not hiding this
from me like everything else, but then /F is right (as always
it would seem) I should not be using such a deprecated thing like
commands, I will switch to subprocess...
I'm even more surprised since I do so much shell scripting and I've
never even heard of this thing before, I guess only the really
battle-scarred old skool ones may know of it.
-h
Hari Sekhon
Scott David Daniels wrote:
Steve Holden wrote:
Hari Sekhon wrote:
I'm running a command like
import commands
result = commands.getstatusoutput('somecommand')
print result[0]
3072
...
No, it's just returning the error code in the top half of a sixteen-bit
value. You will notice that 3072 == 2 * 256.
For the rest of us playing along at home, there is a typo there:
The preceding line should read:
value. You will notice that 3072 == 12 * 256.
--Scott David Daniels
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
Re: commands.getstatusoutput result is not command line exit value!!!
In article [EMAIL PROTECTED], Steve Holden [EMAIL PROTECTED] wrote: Basically the value you want is shifted up 8 bits. Perhaps I should more understandably have said: 12 8 == 3072 Or as already suggested in other followups, use os.WEXITSTATUS (and os.WIFEXITED.) Not only does this do more precisely the right thing, it will work on any platform that supports a POSIX wait -- which doesn't require that exit == status 8, only that WEXITSTATUS be able to return that value. Donn Cave, [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
