cloudmesh-cmd5 1.4.6

A dynamic extensible CMD based command shell

An dynamically extensible CMD based command shell

Requirements

• Python 3.6.2

• Python 2.7.13

Installation from source

Setup a virtualenv either with virtualenv or pyenv. We have a tutorial on cloudmesh classes for the use of pyenv

https://cloudmesh.github.io/classes/lesson/prg/python.html?managing-custom-python-installs#managing-custom-python-installs

Now you need to get two source directories. We assume yo place them in ~/github:

mkdir ~/github
cd ~/github
git clone https://github.com/cloudmesh/cloudmesh.common.git
git clone https://github.com/cloudmesh/cloudmesh.cmd5.git
git clone https://github.com/cloudmesh/cloudmesh.bar.git
 git clone https://github.com/cloudmesh/cloudmesh.sys.git

The cmd5 repository contains the shell, while the extbar directory contains the sample commands foo and bar. The common library contains some useful classes and methods that we also share with other cloudmesh code.

To install them from source simply to the following. The cloudmesh.bar example you want as source as you want to modify the code at one point:

cd ~/github/cloudmesh.common
python setup.py install
pip install .
cd ~/github/cloudmesh.cmd5
python setup.py install
pip install .
cd ~/github/cloudmesh.sys
python setup.py install
pip install .

Instalation from pip

Note

we do recommend that you install cmd5 from source as not all features will be accessible to you if you do a pip install

To install cmd5 from pip please use:

pip install cloudmesh.cmd5

The cloudmesh.bar repository you want to download as source so you can learn how to write your own commands:

mkdir ~/github
cd ~/github
git clone https://github.com/cloudmesh/cloudmesh.bar.git

Commands are shared in the cloudmesh namespace.

The better method on writing a command is to install cloudmesh.sys and use the sys command to generate a new command template via a program. You can generate a new command with:

cms sys command generate NAME

A directory with the name cloudmesh.NAME will be generated that contains the template for the command NAME.

Execution

to run the shell you can activate it with the cms command. cms stands for cloudmesh shell:

(ENV2) $ cms

It will print the banner and enter the shell:

+-------------------------------------------------------+
|   ____ _                 _                     _      |
|  / ___| | ___  _   _  __| |_ __ ___   ___  ___| |__   |
| | |   | |/ _ \| | | |/ _` | '_ ` _ \ / _ \/ __| '_ \  |
| | |___| | (_) | |_| | (_| | | | | | |  __/\__ \ | | | |
|  \____|_|\___/ \__,_|\__,_|_| |_| |_|\___||___/_| |_| |
+-------------------------------------------------------+
|                  Cloudmesh CMD5 Shell                 |
+-------------------------------------------------------+

cms>

To see the list of commands you can say:

cms> help

To see the manula page for a specific command, please use:

help COMMANDNAME

Extension

One of the most important features of CMD5 is its ability to extend it with new commands. This is done via packaged name spaces. This is defined in the setup.py file of your enhancement. The best way to create an enhancement is to take a look at the code in

• https://github.com/cloudmesh/cloudmesh.bar.git

Simply copy the code and modify the bar and foo commands to fit yor needs.

Wraning: do not copy the .git directory

It is important that all objects are defined in the command itself and that no global variables be use in order to allow each shell command to stand alone. Naturally you should develop API libraries outside of the cloudmesh shell command and reuse them in order to keep the command code as small as possible. We place the command in:

cloudmsesh/COMMANDNAME/command/COMMANDNAME.py

An example for the bar command is presented at:

• https://github.com/cloudmesh/cloudmesh.bar/blob/master/cloudmesh/bar/command/bar.py

It shows how simple the command definition is (bar.py):

from __future__ import print_function
from cloudmesh.shell.command import command
from cloudmesh.shell.command import PluginCommand

class BarCommand(PluginCommand):

    @command
    def do_bar(self, args, arguments):
        """
        ::

          Usage:
                command -f FILE
                command FILE
                command list
          This command does some useful things.
          Arguments:
              FILE   a file name
          Options:
              -f      specify the file
        """
        print(arguments)

An important difference to other CMD solutions is that our commands can leverage (besides the standrad definition), docopts as a way to define the manual page. This allows us to use arguments as dict and use simple if conditions to interpret the command. Using docopts has the advantage that contributors are forced to think about the command and its options and document them from the start. Previously we used not to use docopts and argparse was used. However we noticed that for some contributions the lead to commands that were either not properly documented or the developers delivered ambiguous commands that resulted in confusion and wrong ussage by the users. Hence, we do recommend that you use docopts.

The transformation is enabled by the @command decorator that takes also the manual page and creates a proper help message for the shell automatically. Thus there is no need to introduce a sepaarte help method as would normally be needed in CMD.

Features

The following changes are available in the cloudmesh.cmd5 and cloudmesh.common, that are available as source. So you must clone them. They are not yet available in pypi

Execution shell commands

You can execute shell commands when the beginning charater is !

cms \!pwd
cms shell pwd

Timers

To switch timers on or off you can use

cms var timer=on

Than every command you type is timed:

$ cms banner hallo
banner
######################################################################
# hallo
######################################################################
Timer: 0.0011s (banner hallo)

Variables

you can store variables with:

var a=1

you can access them on the commandline with

var.a
\$a

You can list all variables with:

var list

OS Variables can also be integrated. os.HOME will be replaced with the HOME variable from the shell, try it with:

cms banner os.HOME

Defaults

Defaults are variables with a context in which the default applies. For example we can set default images for a cloud. General defaults are placed in the context general. To set the default cloud you can use:

default cloud=kilo

To List the defaults use:

default list

To use the defaults in a command preceed it with the the keyword default. and append the context and the name of the default variable. If the context is missing, the general context will be used. Examples:

banner default.cloud
default image=ubnuntu --context=chameleon
banner default.chameleon.image

Stopwatch

for some (not all) benchmarks this could be helpful. It only works in script mode of cmd5

put this in a file called s.cm:

stopwatch start g
stopwatch stop g
stopwatch print g

Then execute:

cat s.cm | cms

You will get something like this:

cat s.cm | cms


+-------------------------------------------------------+
|   ____ _                 _                     _      |
|  / ___| | ___  _   _  __| |_ __ ___   ___  ___| |__   |
| | |   | |/ _ \| | | |/ _` | '_ ` _ \ / _ \/ __| '_ \  |
| | |___| | (_) | |_| | (_| | | | | | |  __/\__ \ | | | |
|  \____|_|\___/ \__,_|\__,_|_| |_| |_|\___||___/_| |_| |
+-------------------------------------------------------+
|                  Cloudmesh CMD5 Shell                 |
+-------------------------------------------------------+
cms> Timer g started ...
cms> Timer g started ...
cms> Timer g: 0.000274181365967 s