Python Paramiko - Run command

Question

I'm try to run this script:

hostname = '192.168.3.4'
port = 22
username = 'username'
password = 'mypassword'
y = "2012"
m = "02"
d = "27"

if __name__ == "__main__":
   s = paramiko.SSHClient()
   s.load_system_host_keys()
   s.connect(hostname, port, username, password)
   command = 'ls /home/user/images/cappi/03000/y/m/d'
   s.close

The question is: how can I put the variables y,m,d into the variable command ?

Leogout · Accepted Answer · 2022-11-22 21:45:38Z

24

Python has lots of ways to perform string formatting. One of the simplest is to simply concatenate the parts of your string together:

#!/usr/bin/env python
import paramiko

hostname = "192.168.3.4"
port = 22
username = "username"
password = "mypassword"
y = "2012"
m = "02"
d = "27"

def do_it():
    s = paramiko.SSHClient()
    s.load_system_host_keys()
    s.connect(hostname, port, username, password)
    command = "ls /home/user/images/cappi/03000/" + y + "/" + m + "/" + d
    stdin, stdout, stderr = s.exec_command(command)
    for line in stdout.readlines():
        print line
    s.close()

if __name__ == "__main__":
    do_it()

edited Nov 22, 2022 at 21:45

Leogout

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answered Feb 27, 2012 at 19:01

mattbornski

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6 Comments

mattbornski Over a year ago

I don't see that that's significantly better. Now if you had said '/'.join([y, m, d]) you'd have a case.

cha0site Over a year ago

The problem here is not syntax, the problem is that if you run a1 + a2 + a3 + ... + an, you're creating and destroying n-1 temporary strings. join in Python only creates 1 string. This is a bad habit to get into.

mattbornski Over a year ago

I would point out 1. n is very small here, 2. the + operator is very readable here, and 3. greaterdebater.com/blog/gabe/post/7

cha0site Over a year ago

@matt: I think we're going to have to agree to disagree here. This is a convention, and getting in the habit of doing it properly is best, IMO.

kagronick Over a year ago

Using the plus sign for string concatenation is the most un-Pythonic way to do it. Python has like 4 ways to format stings. Percent encoding, f strings, .format, and templates are all preferred over the plus sign. ALSO escape terminal input. pipes.quote is there for a reason.

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BioGeek · Accepted Answer · 2012-02-28 15:37:34Z

4

Using the new format specifications, you can access arguments by name:

'ls /home/user/images/cappi/03000/{year}/{month}/{day}'.format(year=y, month=m, day=d)

answered Feb 28, 2012 at 15:37

BioGeek

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3 Comments

kagronick Over a year ago

You need to put an f in front of the string.

BioGeek Over a year ago

@kagronick since Python 3.6 you can use f-strings (PEP 498), but the above .format(...) string is perfectly valid since Python 2.6 and in Python 3.x.

kagronick Over a year ago

Oh I didn't scroll to the right on my phone. .format was new in 2006 so I assumed f strings were what you were talking about.

cucu8 · Accepted Answer · 2021-09-26 17:07:12Z

4

I prefer

command = f"ls /home/user/images/cappi/03000/{y}/{m}/{d}"

answered Sep 26, 2021 at 17:07

cucu8

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Comments

V123456 · Accepted Answer · 2012-02-27 19:20:47Z

3

command = 'ls /home/user/images/cappi/03000/%s/%s/%s' %(y,m,d)

answered Feb 27, 2012 at 19:20

V123456

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