Python,Shell: How to extract data and store in a iterable varible(specifically in list)?

I am working on my own project. In which these steps have to be performed:

Connect to remote server.
Get pid, process name, cpu usage, swap memory usage by each running process on remote server daily on some specific time(say at 4'0 clock).
I have to compare every day's result with previous day's result (e.g. day1-pid with day2 pid and day1 process name with day2 process name etc.)

So far I have done up to step-2. Now I want to know that how to extract the pid, process name, cpu usage, swap memory usage from remote server and store it in some iterable variable. So that I can compare it for checking memory spike? Any other way apart from my idea will be appreciable. My code sample is like this:

import paramiko
import re
import psutil
class ShellHandler:
    def __init__(self, host, user, psw):
        self.ssh = paramiko.SSHClient()
        self.ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        self.ssh.connect(host, username=user, password=psw, port=22)

        channel = self.ssh.invoke_shell()
        self.stdin = channel.makefile('wb')
        self.stdout = channel.makefile('r')

    def __del__(self):
        self.ssh.close()

    @staticmethod
    def _print_exec_out(cmd, out_buf, err_buf, exit_status):
        print('command executed: {}'.format(cmd))
        print('STDOUT:')
        for line in out_buf:
            print(line, end="")
        print('end of STDOUT')
        print('STDERR:')
        for line in err_buf:
            print(line, end="")
        print('end of STDERR')
        print('finished with exit status: {}'.format(exit_status))
        print('------------------------------------')
        #print(psutil.pids())

        pass

    def execute(self, cmd):
        """

        :param cmd: the command to be executed on the remote computer
        :examples:  execute('ls')
                execute('finger')
                execute('cd folder_name')
        """
        cmd = cmd.strip('\n')
        self.stdin.write(cmd + '\n')
        finish = 'end of stdOUT buffer. finished with exit status'
        echo_cmd = 'echo {} $?'.format(finish)
        self.stdin.write(echo_cmd + '\n')
        shin = self.stdin
        self.stdin.flush()

        shout = []
        sherr = []
        exit_status = 0
        for line in self.stdout:
            if str(line).startswith(cmd) or str(line).startswith(echo_cmd):
                # up for now filled with shell junk from stdin
                shout = []
            elif str(line).startswith(finish):
                # our finish command ends with the exit status
                exit_status = int(str(line).rsplit(maxsplit=1)[1])
                if exit_status:
                    # stderr is combined with stdout.
                    # thus, swap sherr with shout in a case of failure.
                    sherr = shout
                    shout = []
                break
            else:
                # get rid of 'coloring and formatting' special characters
                shout.append(re.compile(r'(\x9B|\x1B\[)[0-?]*[ -/]*[@-~]').sub('', line).replace('\b', '').replace('\r', ''))

        # first and last lines of shout/sherr contain a prompt
        if shout and echo_cmd in shout[-1]:
            shout.pop()
        if shout and cmd in shout[0]:
            shout.pop(0)
        if sherr and echo_cmd in sherr[-1]:
            sherr.pop()
        if sherr and cmd in sherr[0]:
            sherr.pop(0)

        self._print_exec_out(cmd=cmd, out_buf=shout, err_buf=sherr, exit_status=exit_status)
        return shin, shout, sherr

obj=ShellHandler('Servername','username','password')
pID=[]
## I want this(pid, cmd, swap memory) to store in a varible which would be iterable.
pID=ShellHandler.execute(obj,"ps -eo pid,cmd,lstart,%mem,%cpu|awk '{print $1}'")
print(pID[0])##---------------------------------Problem not giving any output.

Solution

Your ShellHandler's execute method returns three items, the first of which is the input you sent to it.

You should probably call it directly like this, anyway:

obj = ShellHandler('Servername','username','password')
in, out, err = obj.execute("ps -eo pid,lstart,%mem,%cpu,cmd")
for line in out.split('\n'):
    pid, lstartwd, lstartmo, lstartdd, lstartm, lstartyy, mem, cpu, cmd = line.split(None, 8)

I moved cmd last because it might contain spaces. The lstart value also contains multiple space-separated fields. Here's what the output looks like in Debian:

19626 Tue Jan 15 15:03:57 2019  0.0  0.0 less filename

There are many questions about how to parse ps output in more detail; I'll refer you to them for figuring out how to handle the results from split exactly.