[Tutor] Remote access from Windows PC to a Linux box

[Mike Baker]

Hi,

I'm trying to connect to a Linux box from my Windows machine and execute a
series of commands - (ls, pwd, cat 'somefile', etc...).   I'm using Putty to
do the ssh and have set up with Putty's Pagent agent to allow me to enter a
passphrase once per session to handle security keys between the two boxes
(so, no passwords needed for my remote scripts).

I have code that will give me a remote prompt on the Linux machine where I
can manually enter commands. This works great, but I want a script to always
execute the same series of commands without having to do so manually.   I
also have code that will execute a single command like cat a file and write
the ouput to a new file. However, when I try to use the communicate object
in subprocess, my window hangs.

Here is my working code:
# module name data_collect.y
#
import subprocess

def simp_tst0(s_name):
    # Opens a remote connection to "s_name and gives a prompt.
    # Works great for executing linux commands.
    # Does not exit gracefully when you type exit. The python
    # prompt hangs when it gets to the r.communicate command
    #
    cmmnd_0="C:\\Progra~1\\putty\\plink %s" % s_name
    r = subprocess.Popen("%s" % cmmnd_0,shell=False)
    (r_stdout, r_stderr) = r.communicate("dir")
    #status=r.poll()     #Locks up if you try to poll here
    print r_stdout
    return r

def cat_remote(s_name, file2cat):
    # This simple test file opens a remote connection to "s_name", does a
cat on
    # file "file2cat" and writes the cat to an output file (out2.txt).
    cmmnd_2="C:\\Progra~1\\putty\\plink %s cat %s" % (s_name, file2cat)
    q = subprocess.Popen("%s" % cmmnd_2, stdout=open('out2.txt','w'))


def simp_tst3(s_name):
    # Runs the initial subprocess.Popen command - creates proc.
    # Hangs when you try to use proc.communicate
    proc = subprocess.Popen(['C:\\Progra~1\\putty\\plink','Sula'],
                        shell=True,
                        stdin=subprocess.PIPE,
                        stdout=subprocess.PIPE,
                        )
    #Either of the next two commands cause window to hang
    #proc.stdin.write("dir")
    #(stdout_value, stderr_value) = proc.communicate(input="dir")[0]
    return proc

Thanks,

Mike
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