Re: Using sudo to write to a file as root from a script
Am 09.08.2013 05:47, schrieb David: On 9 August 2013 14:11, Adam Mercer ramer...@gmail.com wrote: I'm trying to write a script that writes some content to a file root through sudo, but it's not working at all. I am using: [...] At a quick glance, I have a couple of suggestions. command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file] sudo doesn't work like this. It doesn't read from standard input. You need to supply the command as an argument to sudo. Get the sudo syntax correct by learning to use it in a shell (eg terminal running bash ) before trying to use it from python code. Also, I think that passing the pipe character '|' as an argument to Popen is not the correct way to use pipes. So, if you figure out how to use sudo without '|' you will solve both these issues. Or try to change the permissions os.system(chmod 666 config_file) do what you want with the file and set the permissions back to their original state. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On Thu, Aug 8, 2013 at 11:47 PM, David bouncingc...@gmail.com wrote:
At a quick glance, I have a couple of suggestions.
command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file]
sudo doesn't work like this. It doesn't read from standard input. You
need to supply the command as an argument to sudo. Get the sudo syntax
correct by learning to use it in a shell (eg terminal running bash )
before trying to use it from python code.
The above does works in the terminal:
[ram@cizin ~]$ ls -l /opt/ldg/etc/
total 20
-rw-rw-r-- 1 ram admin 5246 Jun 14 15:15 globus-user-env.csh
-rw-rw-r-- 1 ram admin 3388 Jun 14 15:15 globus-user-env.sh
-rw-rw-r-- 1 ram admin 91 Jun 24 11:33 ldg.conf
-rw-r--r-- 1 ram admin5 Jun 14 15:24 os.conf
$ echo -n stable | sudo tee /opt/ldg/etc/channel.conf /dev/null
Password:
$ ls -l /opt/ldg/etc/
total 24
-rw-r--r-- 1 root admin6 Aug 9 07:59 channel.conf
-rw-rw-r-- 1 ram admin 5246 Jun 14 15:15 globus-user-env.csh
-rw-rw-r-- 1 ram admin 3388 Jun 14 15:15 globus-user-env.sh
-rw-rw-r-- 1 ram admin 91 Jun 24 11:33 ldg.conf
-rw-r--r-- 1 ram admin5 Jun 14 15:24 os.conf
$
Thats why I'm trying to use it.
Also, I think that passing the pipe character '|' as an argument to
Popen is not the correct way to use pipes.
I believe subprocess uses pipes as follows
import subprocess
with open(/opt/ldg/etc/channel.conf,w) as out:
subprocess.Popen(command, stdout=out)
Then the file wouldn't be opened as root? And if the file already
exists then I wouldn't be able to open it due to incorrect
permissions.
So, if you figure out how to use sudo without '|' you will solve both
these issues.
I'm open to suggestions as everything I can find involved pipes or
redirections and neither seems to work with subprocess. I can use
subprocess.call() as in:
import subprocess
import sys
channel='stable'
config_file='/opt/ldg/etc/channel.conf'
command=echo -n %s | sudo tee %s /dev/null % (channel, config_file)
try:
retcode = subprocess.call(command, shell=True)
if retcode 0:
sys.exit('Error: Failed to set channel.conf')
except OSError as e:
sys.exit('Error: Execution failed %s' % e)
But I was under the impression that Popen was the preferred approach
to running external processes?
Cheers
Adam
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Re: Using sudo to write to a file as root from a script
On Fri, Aug 9, 2013 at 2:21 PM, Adam Mercer ramer...@gmail.com wrote: command=echo -n %s | sudo tee %s /dev/null % (channel, config_file) You shouldn't need to use 'echo' here. Just provide tee with the text on its standard input, and don't bother with the pipe at all. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
Op 09-08-13 15:29, Chris Angelico schreef: On Fri, Aug 9, 2013 at 2:21 PM, Adam Mercer ramer...@gmail.com wrote: command=echo -n %s | sudo tee %s /dev/null % (channel, config_file) You shouldn't need to use 'echo' here. Just provide tee with the text on its standard input, and don't bother with the pipe at all. That is probably beside the point. I suspect Adam is just giving a minimal example to show the kind of thing he is trying to do. Nit picking the specific example instead of advising on the problem is likely to be less than helpful. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On Fri, Aug 9, 2013 at 8:29 AM, Chris Angelico ros...@gmail.com wrote: You shouldn't need to use 'echo' here. Just provide tee with the text on its standard input, and don't bother with the pipe at all. Thanks, that's much better! Cheers Adam -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On Fri, Aug 9, 2013 at 8:42 AM, Antoon Pardon antoon.par...@rece.vub.ac.be wrote: That is probably beside the point. I suspect Adam is just giving a minimal example to show the kind of thing he is trying to do. Nit picking the specific example instead of advising on the problem is likely to be less than helpful. It is a simplified example, but in this case the nitpicking was very helpful. Caused me to think about the problem differently, and therefore come up with a neater solution. Cheers Adam -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
Op 09-08-13 06:11, Adam Mercer schreef: Hi I'm trying to write a script that writes some content to a file root through sudo, but it's not working at all. I am using: channel = 'stable' config_file = '/opt/ldg/etc/channel.conf' command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file] p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE) out, _ = p.communicate() But it seems as if this isn't doing anything. I just want to write the contents of the variable channel to the file /opt/ldg/etc/channel.conf. But whatever I try just doesn't work. Can anyone offer any pointers? Cheers Adam subprocess.Popen by default doesn't use a shell. That could mean that the equivallent shell command you are trying to execute is: echo -n stable '|' sudo tee /opt/ldg/etc/channel.conf instead of echo -n stable | sudo tee /opt/ldg/etc/channel.conf which you probably want. You should also take care with the echo command. Echo is usually a shell builtin that can behave differently than the echo command. You should make sure you are using the one you actually want to use. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On Fri, Aug 9, 2013 at 2:50 PM, Adam Mercer ramer...@gmail.com wrote: On Fri, Aug 9, 2013 at 8:42 AM, Antoon Pardon antoon.par...@rece.vub.ac.be wrote: That is probably beside the point. I suspect Adam is just giving a minimal example to show the kind of thing he is trying to do. Nit picking the specific example instead of advising on the problem is likely to be less than helpful. It is a simplified example, but in this case the nitpicking was very helpful. Caused me to think about the problem differently, and therefore come up with a neater solution. It wasn't nitpicking so much as suggesting a more Pythonic way to do things. It's entirely plausible that the response would have been Actually, the real command is more complicated than 'echo' so I really do need a pipe, but it's *very* common in shell scripts to call on an external process to do something that in other languages is a builtin. For instance, how do you get the name of the parent of your current directory in bash? Something along the lines of: parent=$(dirname $(pwd$)$) which executes two external commands. In Python, it would be: os.path.dirname(os.getcwd()) which is two internal function calls. It's just one of the things to consider when porting code from one language to another - I wouldn't often use a list comprehension in bash, and I wouldn't often want a pipe between two external processes in Python. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On 9 August 2013 23:21, Adam Mercer ramer...@gmail.com wrote: On Thu, Aug 8, 2013 at 11:47 PM, David bouncingc...@gmail.com wrote: At a quick glance, I have a couple of suggestions. command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file] sudo doesn't work like this. It doesn't read from standard input. You need to supply the command as an argument to sudo. Get the sudo syntax correct by learning to use it in a shell (eg terminal running bash ) before trying to use it from python code. The above does works in the terminal: Ah, sorry, I didn't pay close attention to what you are doing (with tee). So, if you figure out how to use sudo without '|' you will solve both these issues. At least I wasn't 100% wrong :) Anyway I'm glad some smarter people helped you. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On Thu, 08 Aug 2013 23:11:09 -0500, Adam Mercer wrote:
I'm trying to write a script that writes some content to a file root
through sudo, but it's not working at all. I am using:
command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file]
You can't create a pipeline like this. All of the list elements after the
first will be passed as arguments to echo.
Try:
command = ['sudo', 'tee', config_file]
p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, _ = p.communicate('channel')
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Re: Using sudo to write to a file as root from a script
On Fri, 09 Aug 2013 21:12:20 +0100, Nobody wrote:
Try:
command = ['sudo', 'tee', config_file]
p = subprocess.Popen(command, stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
out, _ = p.communicate('channel')
Oops; you also need stdin=subprocess.PIPE.
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Using sudo to write to a file as root from a script
Hi I'm trying to write a script that writes some content to a file root through sudo, but it's not working at all. I am using: channel = 'stable' config_file = '/opt/ldg/etc/channel.conf' command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file] p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE) out, _ = p.communicate() But it seems as if this isn't doing anything. I just want to write the contents of the variable channel to the file /opt/ldg/etc/channel.conf. But whatever I try just doesn't work. Can anyone offer any pointers? Cheers Adam -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On Thu, 08 Aug 2013 23:11:09 -0500, Adam Mercer wrote: Hi I'm trying to write a script that writes some content to a file root through sudo, but it's not working at all. I am using: channel = 'stable' config_file = '/opt/ldg/etc/channel.conf' command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file] p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE) out, _ = p.communicate() But it seems as if this isn't doing anything. I just want to write the contents of the variable channel to the file /opt/ldg/etc/channel.conf. But whatever I try just doesn't work. Can anyone offer any pointers? Do you find anything with: $ grep sudo /var/log/auth.log (you may need to specify a different log) Is the process that's trying to use the sudo command allowed to do so without a password? man sudoers Note - after editing /etc/sudoers you must set the permissions back to 440 -- Denis McMahon, denismfmcma...@gmail.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Using sudo to write to a file as root from a script
On 9 August 2013 14:11, Adam Mercer ramer...@gmail.com wrote: I'm trying to write a script that writes some content to a file root through sudo, but it's not working at all. I am using: [...] At a quick glance, I have a couple of suggestions. command = ['echo', '-n', channel, '|', 'sudo', 'tee', config_file] sudo doesn't work like this. It doesn't read from standard input. You need to supply the command as an argument to sudo. Get the sudo syntax correct by learning to use it in a shell (eg terminal running bash ) before trying to use it from python code. Also, I think that passing the pipe character '|' as an argument to Popen is not the correct way to use pipes. So, if you figure out how to use sudo without '|' you will solve both these issues. -- http://mail.python.org/mailman/listinfo/python-list
