ssh with Subprocess.popen

Question

Hello All i'm stuck with a small problem. May be i'm missing something obvious but i'm unable to figure out the problem. I've GUI where i have a button named "erp" and if i press that it should do an ssh first to a machine named (host id name) 'ayaancritbowh91302xy' and then it should execute commands like (cd change dir) and 'ls -l'. I've tried the following code:

def erptool():
    sshProcess = subprocess.Popen(['ssh -T', 'ayaancritbowh91302xy'],stdin=subprocess.PIPE, stdout = subprocess.PIPE)
    sshProcess.stdin.write("cd /home/thvajra/transfer/08_sagarwa\n")
    sshProcess.stdin.write("ls -l\n")
    sshProcess.stdin.write("echo END\n")
    for line in stdout.readlines():
        if line == "END\n":
        break
        print(line)

i got the following error:

Traceback (most recent call last):
  File "Cae_Selector.py", line 34, in erptool
    for line in stdout.readlines():
NameError: global name 'stdout' is not defined
Pseudo-terminal will not be allocated because stdin is not a terminal.

How to do this? can anyone help me with this?

start by fixing the stdout error: try adding "from sys import stdout" or change it to sshProcess.stdout if that's what you mean. — Nick Russo
– Nick Russo, Commented Oct 7, 2014 at 2:45
consider adding a '-T' after 'ssh', so that ssh won't even try to allocate a pseudo-terminal. — Nick Russo
– Nick Russo, Commented Oct 7, 2014 at 2:45
i used '-t' after ssh now i got the following error: File "Cae_Selector.py", line 35, in erptool for line in stdout.readlines(): IOError: File not open for reading usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec] [-D [bind_address:]port] [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11] [-i identity_file] [-L [bind_address:]port:host:hostport] [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port] [-Q cipher | cipher-auth | mac | kex | ke — ayaan
– ayaan, Commented Oct 7, 2014 at 2:50
@ayaan If you want to keep the ssh process open in the background, don't use communicate but take a look at the accepted answer for stackoverflow.com/questions/375427/… — metatoaster
– metatoaster, Commented Oct 7, 2014 at 3:41

Nick Russo · Accepted Answer · 2014-10-07 03:16:37Z

5

Try this:

#!/usr/bin/env python
import subprocess
def erptool():
    sshProcess = subprocess.Popen(['ssh', '-T', 'ayaancritbowh91302xy'],
                                  stdin=subprocess.PIPE, stdout=subprocess.PIPE)
    out, err = sshProcess.communicate("cd /home/thvajra/transfer/08_sagarwa\nls -l\n")
    print(out),
erptool()

I added -T so ssh wouldn't try to allocate a pseudo-tty, and avoid END and stdout issues by using communicate.

edited Oct 7, 2014 at 3:16

answered Oct 7, 2014 at 2:52

Nick Russo

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jfs · Accepted Answer · 2014-10-07 03:07:41Z

4

To execute several shell commands via ssh:

#!/usr/bin/env python3
from subprocess import Popen, PIPE

with Popen(['ssh', '-T', 'ayaancritbowh91302xy'],
           stdin=PIPE, stdout=PIPE, stderr=PIPE,
           universal_newlines=True) as p:
    output, error = p.communicate("""            
        cd /home/thvajra/transfer/08_sagarwa
        ls -l
        """)
    print(output)
    print(error)
    print(p.returncode)

output contains stdout, error -- stderr, p.returncode -- exit status.

answered Oct 7, 2014 at 3:07

jfs

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2 Comments

ayaan Over a year ago

so if i want to open a software will this method [email protected]

jfs Over a year ago

@ayaan: it depends on software. Your comment to the other answer suggests that you want to run matlab, see Run Matlab in Linux without graphical environment?: try matlab -nodesktop. If it doesn't work, update your question or ask a new one.

user2879704 · Accepted Answer · 2014-10-07 02:47:23Z

0

It must be sshProcess.stdout.readLines() as you are talking to the process's stdout....

answered Oct 7, 2014 at 2:47

user2879704

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