Python subprocess.call() apparently not working with psexec

Question

I am having an issue executing remote processes with subprocess.call() and psexec. I am using the following syntax for executing the process remotely with subprocess.call() :

def execute(hosts):
    ''' Using psexec, execute the script on the list of hosts '''
    successes = []

    wd = r'c:\\'
    file = r'c:\\script.exe'
    for host in hosts:
        res = subprocess.call(shlex.split(r'psexec \\%s -e -s -d -w %s %s ' % (host,wd,file)), stdin=None, stdout=None, stderr=None)
        if res == 0:
           successes.append(host)   
        else:
            logging.warning("Error executing script on host %s with error code %d" % (host, res))

    print shlex.split(r'psexec \\%s -e -s -d -w %s %s ' % (hosts[0],wd,file))
    return successes 

As you can see, as part of my troubleshooting, I am printing the shlex.split() output to ensure that it is what I want. This print statement gives:

['psexec', '\\HOSTNAME', '-e', '-s', '-d', '-w', 'c:\\', 'c:\\script.exe']

Which is what I would expect. Unfortunately, when I run it, I get an error saying:

PsExec could not start \GN-WRK-02:
The system cannot find the file specified.

Directly after this, I run the psexec command with the exact syntax that the program should be running it with (judging by the shlex.split() output) and it works completely fine. My syntax is:

psexec \\HOSTNAME -e -s -d -w c:\\ c:\\script.exe

Any ideas why this wouldn't be working? If it matters the execute function is being called through multiprocessing's map() function on two or 3 host lists.

Any help would be great! Thanks!

Answer 1

Your \\\\ double slash in front of the hostname is just one slash; it is doubled to escape the slash.

You can see this in the shlex.split() output:

['psexec', '\\HOSTNAME', '-e, '-s', '-d', '-w', 'c:\\', 'c:\\script.exe']

note that \\\\ before the hostname is just the two backslashes, just like in the c:\\\\ filename value. . If you print just that value you see that the backslash at the sart is just one character:

>>> print '\\HOSTNAME'
\HOSTNAME
>>> '\\HOSTNAME'[0]
'\\'
>>> '\\HOSTNAME'[1]
'H'

That's because shlex.split() is a POSIX tool, not a Windows tool, and it interprets the \\\\ in the raw string as an escape too; if you are using that tool, double the slashes again:

shlex.split(r'psexec \\\\%s -e -s -d -w %s %s ' % (host,wd,file))

An alternative may be to disable POSIX mode, but I am not entirely certain how that would interplay with Windows:

shlex.split(r'psexec \\%s -e -s -d -w %s %s ' % (host,wd,file), posix=False)