Check whether a path exists on a remote host using

问题:

Paramiko's SFTPClient apparently does not have an exists method. This is my current implementation:

def rexists(sftp, path):
    """os.path.exists for paramiko's SCP object
    """
    try:
        sftp.stat(path)
    except IOError, e:
        if 'No such file' in str(e):
            return False
        raise
    else:
        return True

Is there a better way to do this? Checking for substring in Exception messages is pretty ugly and can be unreliable.

回答1:

See the errno module for constants defining all those error codes. Also, it's a bit clearer to use the errno attribute of the exception than the expansion of the __init__ args, so I'd do this:

except IOError, e: # or "as" if you're using Python 3.0
  if e.errno == errno.ENOENT:
    ...

回答2:

There is no "exists" method defined for SFTP (not just paramiko), so your method is fine.

I think checking the errno is a little cleaner:

def rexists(sftp, path):
    """os.path.exists for paramiko's SCP object
    """
    try:
        sftp.stat(path)
    except IOError, e:
        if e[0] == 2:
            return False
        raise
    else:
        return True

回答3:

Paramiko literally raises FileNotFound

def sftp_exists(sftp, path):
    try:
        sftp.stat(path)
        return True
    except FileNotFound:
        return False