Re: pipes like perl
many thanks to all the fellows who cared to answer! bye max -- http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
infidel [EMAIL PROTECTED] (i) wrote: i .readlines() won't return until it hits end-of-file, but the man i command waits for user input to scroll the content, like the more or i less commands let you view pages of information on a terminal. man shouldn't wait for user input if its output is a pipe. Try man man|cat. -- Piet van Oostrum [EMAIL PROTECTED] URL: http://www.cs.uu.nl/~piet [PGP 8DAE142BE17999C4] Private email: [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
max(01)* enlightened us with: but i need to check the success/failure of the external command *before* closing the file! You can't, unless you have a more intimite knowledge of the command involved. If you know, for instance, that any output on stderr means an error, you can check for just that. Without knowledge of the command and it's output, the only thing you can check on is the exit code. Sybren -- The problem with the world is stupidity. Not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself? Frank Zappa -- http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
In article [EMAIL PROTECTED], max(01)* [EMAIL PROTECTED] wrote: in perl i can do this: ... but i do not know how to do it in python, because if *command*: gives syntax error. moreover, if i use ... it doesn't work, since *do_something* and *do_something_more* are always executed (it seems like MYPIPE = os.popen(*some_system_command*, r) does not raise any exception even if *some_system_command* does not exist/work... Just to address this last point -- if you're running 2.4, you can get this through the subprocess module. With its popen equivalent, something like subprocess.Popen(cmd, stdout=subprocess.PIPE).stdout will raise an exception if the command is not found. The command in this case would specified as an argv list, not a shell command. The basic problem is that you have to fork first, then exec, and by the time the forked interpreter finds out that the exec didn't work, its parent has gone on to do the I/O it's expecting. I think subprocess gets around that, on UNIX, with a trick involving an extra pipe, that would work only on UNIX. Donn Cave, [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
but... i see it doesn't work for some commands, like man python (it gets stuck on the if line)... .readlines() won't return until it hits end-of-file, but the man command waits for user input to scroll the content, like the more or less commands let you view pages of information on a terminal. -- http://mail.python.org/mailman/listinfo/python-list
pipes like perl
hi.
in perl i can do this:
...
if (open (MYPIPE, *some_system_command* |))
{
...
*do_something*
...
while ($answer = MYPIPE)
{
print $answer;
}
...
*do_something_more*
...
}
else
{
...
*do_something_else*
...
}
...
but i do not know how to do it in python, because if *command*: gives
syntax error.
moreover, if i use
...
import os
...
try:
MYPIPE = os.popen(*some_system_command*, r)
...
*do_something*
...
for answer in MYPIPE:
print answer,
MYPIPE.close()
...
*do_something_more*
...
except:
...
*do_something_else*
...
...
it doesn't work, since *do_something* and *do_something_more* are
always executed (it seems like
MYPIPE = os.popen(*some_system_command*, r)
does not raise any exception even if *some_system_command* does not
exist/work...
any help?
thanks a lot
max
--
http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
max(01)* wrote:
hi.
(snip)
it doesn't work, since *do_something* and *do_something_more* are
always executed (it seems like
MYPIPE = os.popen(*some_system_command*, r)
does not raise any exception even if *some_system_command* does not
exist/work...
any help?
http://www.python.org/doc/2.4.1/lib/os-newstreams.html#os-newstreams
The exit status of the command (encoded in the format specified for
wait()) is available as the return value of the close() method of the
file object, except that when the exit status is zero (termination
without errors), None is returned.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
Here's one technique I use to run an external command in a particular
module:
stdin, stdout, stderr = os.popen3(cmd)
stdin.close()
results = stdout.readlines()
stdout.close()
errors = stderr.readlines()
stderr.close()
if errors:
raise Exception(''.join(errors))
Maybe this will get you going in a better direction?
--
http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
bruno modulix wrote: max(01)* wrote: hi. (snip) it doesn't work, since *do_something* and *do_something_more* are always executed (it seems like MYPIPE = os.popen(*some_system_command*, r) does not raise any exception even if *some_system_command* does not exist/work... any help? http://www.python.org/doc/2.4.1/lib/os-newstreams.html#os-newstreams The exit status of the command (encoded in the format specified for wait()) is available as the return value of the close() method of the file object, except that when the exit status is zero (termination without errors), None is returned. but i need to check the success/failure of the external command *before* closing the file! -- http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
infidel wrote:
Here's one technique I use to run an external command in a particular
module:
stdin, stdout, stderr = os.popen3(cmd)
stdin.close()
results = stdout.readlines()
stdout.close()
errors = stderr.readlines()
stderr.close()
if errors:
raise Exception(''.join(errors))
Maybe this will get you going in a better direction?
yeah thanks!
i translated as:
import os
CMD_STDIN, CMD_STDOUT, CMD_STDERR = \
os.popen3(*some_system_command*, r)
if not CMD_STDERR.readlines():
...
*do_something*
...
for answer in CMD_STDOUT:
print answer,
...
*do_something_more*
...
else:
...
*do_something_else*
...
CMD_STDIN.close()
CMD_STDOUT.close()
CMD_STDERR.close()
bye
max
--
http://mail.python.org/mailman/listinfo/python-list
Re: pipes like perl
max(01)* wrote:
infidel wrote:
Here's one technique I use to run an external command in a particular
module:
stdin, stdout, stderr = os.popen3(cmd)
stdin.close()
results = stdout.readlines()
stdout.close()
errors = stderr.readlines()
stderr.close()
if errors:
raise Exception(''.join(errors))
Maybe this will get you going in a better direction?
yeah thanks!
i translated as:
.
import os
.
CMD_STDIN, CMD_STDOUT, CMD_STDERR = \
os.popen3(*some_system_command*, r)
if not CMD_STDERR.readlines():
...
*do_something*
...
for answer in CMD_STDOUT:
print answer,
...
*do_something_more*
...
else:
...
*do_something_else*
...
CMD_STDIN.close()
CMD_STDOUT.close()
CMD_STDERR.close()
.
but... i see it doesn't work for some commands, like man python (it
gets stuck on the if line)...
how come?
--
http://mail.python.org/mailman/listinfo/python-list
