使用Python子进程使用ssh的多个命令

Question

I need to execute multiple shell commands in a ssh session using the subprocess module. I am able to execute one command at a time with:

   subprocess.Popen(["ssh",  "-o UserKnownHostsFile=/dev/null", "-o StrictHostKeyChecking=no", "%s" % <HOST>, <command>])

But is there a way to execute multiple shell commands with subprocess in a ssh session? If possible, I don't want to use packages.

Thank you very much!

Answer 1

Strictly speaking you are only executing one command with Popen no matter how many commands you execute on the remote server. That command is ssh .

To have multiple commands executed on the remote server just pass them in your command string seperated by ; s:

commands = ["echo 'hi'",  "echo 'another command'"]
subprocess.Popen([
    "ssh",
    "-o UserKnownHostsFile=/dev/null",
    "-o StrictHostKeyChecking=no",
    ";".join(commands)
])

You could alternatively join commands on && if you wanted each command to only execute if the previous command had succeeded.

If you have many commands and you are concerned that you might exceed the command line limits , you could execute sh (or bash) with the -s option on the remote server, which will execute commands one-by-one as you send them:

p = subprocess.Popen([
    "ssh",
    "-o UserKnownHostsFile=/dev/null",
    "-o StrictHostKeyChecking=no",
    "sh -s",
], stdin=subprocess.PIPE)

for command in commands:
    p.stdin.write(command)
    p.stdin.write("\n")
    p.flush()

p.communicate()

Note that in Python3 you will need to encode the command to a byte string ( command.encode("utf8") ) before writing it to the stdin of the subprocess .

I feel like this is overkill for most simple situations though where the initial suggest is simplest.