Pass Python variable inside command with Paramiko

Question

With this command, I want to save an output of the smartctl command of the sda drive.

Now, since I use RAID, I have multiple drives, not just sda.

The following command works fine:

stdin, stdout, stderr = ssh.exec_command('/bin/su root -c "smartctl -a /dev/sda > /tmp/smartctl_output1"', get_pty=True) # ORIGINAL

I want to achieve that I pass local Python variable "DISK" containing sda, sdb, sdc and so on instead only static value.

The following line produces error:

stdin, stdout, stderr = ssh.exec_command('/bin/su root -c "smartctl -a /dev/" + DISK + " > /tmp/" + DISK', get_pty=True)

edit: tried this as well:

stdin, stdout, stderr = ssh.exec_command('/bin/su root -c "smartctl -a /dev/' + DISK + ' > /tmp/' + DISK, get_pty=True)
stdin.write(ROOTPASS)
stdin.write('\n')
DEBUG1=stdout.read()
print   "DEBUG COMMAND= " + DEBUG1

Produces the following error and file in /tmp/ + DISK not created:

DEBUG COMMAND= bash: -c: line 0: unexpected EOF while looking for matching `"'
bash: -c: line 1: syntax error: unexpected end of file

Answer 1

Your question has nothing to do with Paramiko.

It's just a trivial concatenation of strings in Python:

ssh.exec_command(
     '/bin/su root -c "smartctl -a /dev/' + DISK + ' > /tmp/' + DISK + '"',
     get_pty=True)

For even better options, see How to insert string into a string as a variable?