From our experience, end users rarely read documentation no matter how high- quality or useful that documentation might be. So it is important that you provide good built-in help within your application. Fortunately, cmd2 makes this easy.

Getting Help

cmd2 makes it easy for end users of cmd2 applications to get help via the built-in help command. The help command by itself displays a list of the commands available:

(Cmd) help

Documented commands (use 'help -v' for verbose/'help <topic>' for details):
alias  help     ipy    py    run_pyscript  set    shortcuts
edit   history  macro  quit  run_script    shell

The help command can also be used to provide detailed help for a specific command:

(Cmd) help quit
Usage: quit [-h]

Exit this application

optional arguments:
  -h, --help  show this help message and exit

Providing Help

cmd2 makes it easy for developers of cmd2 applications to provide this help. By default, the help for a command is the docstring for the do_* method defining the command - e.g. for a command foo, that command is implementd by defining the do_foo method and the docstring for that method is the help.

For commands which use one of the argparse decorators to parse arguments, help is provided by argparse. See Help Messages for more information.

Occasionally there might be an unusual circumstance where providing static help text isn’t good enough and you want to provide dynamic information in the help text for a command. To meet this need, if a help_foo method is defined to match the do_foo method, then that method will be used to provide the help for command foo. This dynamic help is only supported for commands which do not use an argparse decorator because didn’t want different output for help cmd than for cmd -h.

Categorizing Commands

By default, the help command displays:

Documented commands (use 'help -v' for verbose/'help <topic>' for details):
alias  help     ipy    py    run_pyscript  set    shortcuts
edit   history  macro  quit  run_script    shell

If you have a large number of commands, you can optionally group your commands into categories. Here’s the output from the example

Documented commands (use 'help -v' for verbose/'help <topic>' for details):

Application Management
deploy  findleakers  redeploy  sessions  stop
expire  list         restart   start     undeploy

Command Management
disable_commands  enable_commands

connect  which

Server Information
resources  serverinfo  sslconnectorciphers  status  thread_dump  vminfo

alias   edit  history  py    run_pyscript  set    shortcuts
config  help  macro    quit  run_script    shell  version

There are 2 methods of specifying command categories, using the @with_category decorator or with the categorize() function. Once a single command category is detected, the help output switches to a categorized mode of display. All commands with an explicit category defined default to the category Other.

Using the @with_category decorator:

def do_which(self, _):
    """Which command"""

Using the categorize() function:

You can call with a single function:

def do_connect(self, _):
    """Connect command"""

# Tag the above command functions under the category Connecting
categorize(do_connect, CMD_CAT_CONNECTING)

Or with an Iterable container of functions:

def do_undeploy(self, _):
    """Undeploy command"""

def do_stop(self, _):
    """Stop command"""

def do_findleakers(self, _):
    """Find Leakers command"""
    self.poutput('Find Leakers')

# Tag the above command functions under the category Application Management
            do_findleakers), CMD_CAT_APP_MGMT)

The help command also has a verbose option (help -v or help --verbose) that combines the help categories with per-command Help Messages:

Documented commands (use 'help -v' for verbose/'help <topic>' for details):

Application Management
deploy              Deploy command
expire              Expire command
findleakers         Find Leakers command
list                List command
redeploy            Redeploy command
restart             usage: restart [-h] {now,later,sometime,whenever}
sessions            Sessions command
start               Start command
stop                Stop command
undeploy            Undeploy command

connect             Connect command
which               Which command

Server Information
resources              Resources command
serverinfo             Server Info command
sslconnectorciphers    SSL Connector Ciphers command is an example of a command that contains
                       multiple lines of help information for the user. Each line of help in a
                       contiguous set of lines will be printed and aligned in the verbose output
                       provided with 'help --verbose'
status                 Status command
thread_dump            Thread Dump command
vminfo                 VM Info command

alias               Manage aliases
config              Config command
edit                Run a text editor and optionally open a file with it
help                List available commands or provide detailed help for a specific command
history             View, run, edit, save, or clear previously entered commands
macro               Manage macros
py                  Invoke Python command or shell
quit                Exits this application
run_pyscript        Runs a python script file inside the console
run_script          Runs commands in script file that is encoded as either ASCII or UTF-8 text
set                 Set a settable parameter or show current settings of parameters
shell               Execute a command as if at the OS prompt
shortcuts           List available shortcuts
version             Version command

When called with the -v flag for verbose help, the one-line description for each command is provided by the first line of the docstring for that command’s associated do_* method.