Test if File/Dir exists over SSH/Sudo in Python/Ba

问题:

This question already has answers here:

Verify a file exists over ssh (6 answers)

Closed 7 years ago.

I am installing certificates on a remote server and want to check whether they exist before I overwrite them. The server only allows non-root access via ssh public key. I can sudo -s to root once in a shell. Root is required because /etc/ssl is not readable by anyone else. This is being developed in python fabric, so any command that can be run in a shell command via sudo would work. I don't mind typing in passwords at prompts in this case.

TL;DR: I need an sh command that can tell my python program whether a remote file (or directory) exists when run as if fabric.sudo(sh_command) == True: (or something similar).

Thank you!

回答1:

from fabric.contrib.files import exists

def foo():
    if exists('/path/to/remote/file', use_sudo=True):
        #command

回答2:

Maybe not the simplest way, but out of my head, I would suggest

ssh user@server 'bash -c "if [ -e /path/to/remote/file ] ; then true ; fi"'

回答3:

Run a command like test in Linux to figure out whether a directory exists or not. The output of fabric.sudo is a multline-string, that can be parsed for the return status.