dumbshell.py

#! /usr/bin/env python3

import os
from sys import exit
from subprocess import call
from shlex import split

allowed_commands = 'ls echo cp mv rm ln whoami sort pwd cd gzip zcat zless ps free df du kill cat mkdir passwd uname whereis locate tail date'.split()
cmd = []

def read_cmd(cmd):
    while not cmd:
        try:
            cmd = split(input('> '))
        except EOFError:
            exit()
    return cmd


def cd(cmd):
    if len(cmd) == 1:
        path = os.path.expanduser('~')
    else:
        path = cmd[1]
    try:
        os.chdir(path)
    except Exception as e:
        print(e)


while True:
    cmd = read_cmd(cmd)
    if cmd[0] in allowed_commands:
        if cmd[0] == 'cd':
            cd(cmd)
        else:
            call(cmd)
    else:
        print(repr(cmd[0]), 'not allowed. Only the following commands are available:', allowed_commands)
    cmd = []