Shell¶

usage: shell_example.py [-h] [-v] [-s] [-f FILE] [-r] [--session SESSION]
                        [cmd ...]

If no positional arguments are given then an interactive subshell is started.

positional arguments:
  cmd                   A comma- or newline-separated list of commands

optional arguments:
  -h, --help            show this help message and exit
  -v, --verbose
  -s, --safe            Safe-mode. Ask for confirmation before executing commands.
  -f FILE, --file FILE  Read and run FILE as a command
  -r, --reload          Reload last session
  --session SESSION     Use SESSION

Default Commands
~~~~~~~~~~~~~~~~~~~~~~~~~~

Run shell commands by prefixing them with `!`.
E.g.
    ./shell.py !echo abc; echo def # Bash

Run multiple Python commands by separating each command with colons or newlines.
E.g.
    ./shell.py 'print abc; print def 
 print ghi'

Variables
~~~~~~~~~~~~~~~~~~~~~~~~~~

Assign constants or evaluate expressiosn:
```
    a = 100
    b <- print $a
    echo $a $b
```

Interopability
~~~~~~~~~~~~~~~~~~~~~~~~~~

Interopability with Bash can be done with pipes:
    `|>` for Python.
    `|`  for Bash
    `>-`  for Bash (write to file)
    `>>`  for Bash (append to file)

1. To stdin and stdout
E.g.
```
    echo abc | ./shell.py print
    ./shell.py print abc | echo
```

2. Within the dsl
E.g.
```
    ./shell.py print abc # Python
    ./shell.py 'print abc | echo'
    ./shell.py 'print abc |> print'
```