`linux memory and insert into textbox below` `i must put 3 methods, for each command>`

***code is:***

class LoginFrame(Frame):

    def __init__(self, master):
        super().__init__(master)
        self.label_ipa       = Label(self, text="IP Address",font=("Times New Roman",14), fg="blue")
        self.label_username = Label(self, text="Username",font=("Times New Roman", 14), height=4, fg="blue")
        self.label_password = Label(self, text="Password",font=("Times New Roman", 14), height=4, fg="blue")
        self.entry_ipa = Entry(self,justify=CENTER)#.grid(row-0,column=1)
        self.entry_username = Entry(self,justify=CENTER)#.grid(row=0,column=1,pady=4)
        self.entry_password = Entry(self, show="*",justify=CENTER)
        self.label_ipa.grid(row=0,sticky=E)
        self.label_username.grid(row=1, sticky=E)
        self.label_password.grid(row=2, sticky=E)
        self.entry_ipa.grid(row=0,column=1)
        self.entry_username.grid(row=1, column=1)
        self.entry_password.grid(row=2, column=1)
        self.disct = Button(self, text="Close Session",command=self._disc_,font=("Times New Roman", 14), width=10,height=2, fg="red")
        self.logbtn = Button(self, text="Connecting", command=self._login_,font=("Times New Roman", 14), width=10,height=2, fg="green")
        self.logbtn.grid(row=3,column=0)
        self.disct.grid(row=3,column=2)
        self.pack()

    def _login_(self):

                ipa = self.entry_ipa.get()

                username = self.entry_username.get()
                password = self.entry_password.get()

                if not ipa:
                    tk.messagebox.showerror("Error MessageBox","please Enter the IP Address",icon="warning")
                    return False

                if not username:
                    tk.messagebox.showerror("Error MessageBox","please Enter Your Username",icon="warning")
                    return False
                if not password:
                    tk.messagebox.showerror("Error MessageBox","please Enter Your Password",icon="warning")
                    return False

                cl1=paramiko.SSHClient()
                cl1.set_missing_host_key_policy(paramiko.AutoAddPolicy())
                cl1.connect(ipa,username=username,password=password)

                if(ipa==ipa and username==username and password==password):

                        tk.messagebox.showinfo("OPEN THE Session","SSH connection to %s established" %ipa)

                else:
        #client_key
                        tk.messagebox.showerror("Error MessageBox","please try again",icon="warning")
                window = Toplevel(root)
                window.title("Command Action")
                window.geometry("400x350+400+350")
                b1=Button(window,text="check Memory",bg="red",command=self._login_).place(x=0,y=0)
                b2=Button(window,text="Free disk Space",bg="red").place(x=100,y=0)
                b3=Button(window,text="Imprt XML FILE",bg="red").place(x=220,y=0)
                text=Text(window,height=10,width=50).place(x=0,y=50)
                stdin, stdout, stderr=cl1.exec_command("free -g")
                #print(stdout.read())
                text.insert(stdout.read())
    def _disc_(self):

          MsgBox = tk.messagebox.askquestion ('Exit Application','Are you sure you want Dissconnecting ',icon = 'warning')

          if MsgBox == "yes":

              root.destroy()

          else:

              tk.messagebox.showinfo('Return','You will now return to the
             application screen')

root = tk.Tk()
root.geometry('400x400+50+50')
root.title('Connecting to Server')
lf = LoginFrame(root)
root.mainloop()