Scripting¶
Operating system shells have long had the ability to execute a sequence of
commands saved in a text file. These script files make long sequences of
commands easier to repeatedly execute. cmd2
supports two similar
mechanisms: command scripts and python scripts.
Command Scripts¶
A command script contains a sequence of commands typed at the the prompt of a
cmd2
based application. Unlike operating system shell scripts, command
scripts can’t contain logic or loops.
Creating Command Scripts¶
Command scripts can be created in several ways:
- creating a text file using any method of your choice
- using the built-in
edit
command to create or edit an existing text file - saving previously entered commands to a script file using
history -s
. See History for more details.
If you create create a text file from scratch, just include one command per
line, exactly as you would type it inside a cmd2
application.
Running Command Scripts¶
Command script files can be executed using the built-in run_script
command
or @
shortcut. Both ASCII and UTF-8 encoded unicode text files are
supported. The run_script
command supports tab-completion of file system
paths. There is a variant _relative_run_script
command or @@
shortcut for use within a script which uses paths relative to the first script.
Comments¶
Any command line input where the first non-whitespace character is a # will be treated as a comment. This means any # character appearing later in the command will be treated as a literal. The same applies to a # in the middle of a multiline command, even if it is the first character on a line.
Comments are useful in scripts, but would be pointless within an interactive session.
(Cmd) # this is a comment
(Cmd) command # this is not a comment
Python Scripts¶
If you require logic flow, loops, branching, or other advanced features, you
can write a python script which executes in the context of your cmd2
app.
This script is run using the run_pyscript
command. A simple example of
using run_pyscript
is shown below along with the arg_printer script:
(Cmd) run_pyscript examples/scripts/arg_printer.py foo bar 'baz 23'
Running Python script 'arg_printer.py' which was called with 3 arguments
arg 1: 'foo'
arg 2: 'bar'
arg 3: 'baz 23'
run_pyscript
supports tab-completion of file system paths, and as shown
above it has the ability to pass command-line arguments to the scripts invoked.
Python scripts executed with run_pyscript
can run cmd2
application
commands by using the syntax:
app(‘command args’)
where:
app
is a configurable name which can be changed by setting thepy_bridge_name
attribute of yourcmd2.Cmd
class instancecommand
andargs
are entered exactly like they would be entered on the command line of yourcmd2
application