Read a file from server with SSH using Python

user_178437 0
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I am trying to read a file from a server using SSH from Python. I am using Paramiko to connect. I can connect to the server and run a command like cat filename and get the data back from the server but some files I am trying to read are around 1 GB or more in size.

How can I read the file on the server line by line using Python?

Additional Info: What is regularly do is run a cat filename command and store the result in a variable and work off that. But since the file here is quite big, I am looking for a way to read a file line by line off the server.

EDIT: I can read a bunch of data and split it into lines but the problem is that the data received in the buffer does not always include the complete lines. For eg, if buffer has 300 lines, the last line may only be half of the line on the server and the next half would be fetched in the next call to the server. I want complete lines

EDIT 2: what command can I use to print lines in a file in a certain range. Like print first 100 lines, then the next 100 and so on? This way the buffer will always contain complete lines.

paramiko ssh python
6 Answers

It looks like back in Sept 2013 paramiko added the ability for these objects to support context managers natively, so if you want both Matt's clean answer with jfs's context manager, now all you need is:

with ssh_client.open_sftp() as sftp_client:
    with sftp_client.open('remote_filename') as remote_file:
        for line in remote_file:
            # process line
user_29698800

I lost almost half a day of work trying to use paramiko and fabric to do this. But thanks to this answer I was able to come up with the following answer:

from ftplib import FTP_TLS

source = '/file/path/in/FTP/server.txt'
destiny = '/file/path/in/local/machine.txt'

with FTP_TLS() as ftps:
  ftps.connect(host, port)
  ftps.sendcmd(f'USER { username }')
  ftps.sendcmd(f'PASS { password }')

  with ftps as conn:
    with open(destiny, 'wb') as file:
      conn.retrbinary(f'RETR { source }', file.write)
user_70929540
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