rocketsh is the interactive shell used to execute commands and run programs. It is launched by init at boot and is always available at the system prompt.

This page describes rocketsh in detail. For a simple overview of using the shell, see The Shell in the User Guide.

Command line entry

The rocketsh shell supports command line editing. You may use the cursor LEFT and RIGHT keys plus HOME and END to navigate in the current line and edit it, inserting into the line if neccessary.

Alternately, you can use the cursor UP and DOWN keys to move through the history of recently entered commands. If you edit one of these commands or send it, it will be inserted into the history again as the latest command.

The history buffer will grow as needed to accomodate as many history items as you enter.

Pressing ESC will abort the current line entry, clearing its contents and advancing down to the line below.

These interactive line editing facilities are also available to any other BASIC programs via the ansi library.

Rocket Shell Commands

The rocketsh shell supports two forms of input; firstly any command you type is searched for as a program under the /programs directory. If it can be found it is executed. The path under which rocketsh searches for programs to run can be changed, as shown below.

If no matching program can be found, the line is passed to EVAL instead and any changes to the program state will be inherited by rocketsh, including documented variables below.

BASIC execution

Any line entered at the prompt which is not resolved to a program is executed using EVAL.

This means the shell accepts full BASIC syntax directly at the prompt, including:

Variable assignment
Expressions
Procedure and function calls
Control flow (via multi-line entry)

All built-in BASIC keywords, operators, and functions are available exactly as they are within a BASIC program.

A = 10
PRINT A * 2
PROCdemo

Single-line input executes in the current shell context.

Multi-line input (see below) executes as an anonymous child program.

Changes made by single-line execution persist in the shell environment.

Multi-line program entry

rocketsh supports entering and executing multi-line BASIC programs directly at the prompt.

Enter [ on a new line to begin multi-line entry mode.
The prompt will change to numbered lines (1, 2, 3, ...).
Enter BASIC statements line by line.
Enter ] on a new line to execute the program.
To abort entering a multi-line program without running it, press ESC
You can use cursor keys to edit and recall previous lines
Each line you enter becomes part of the rocketsh command history

The entered lines are combined and executed using EVAL as an anonymous program.

Built-in commands

cd / chdir

Change the current working directory.

cd /harddisk

chdir subdir

Use / at the start to go to an absolute location.
Without /, the path is taken relative to your current location.

up

Move to the parent directory (one level up).

up

For example, if you are in /programs/tools, up will take you to /programs.

run

Run a program from the directory set in PATH$.

run myprog

This runs the program named myprog from the current program search path.

task

Run a program from PATH$ in the background.

task myprog

The program starts and runs independently, allowing you to continue using the shell.

version

Display version and copyright information for the shell.

version

push

Save the current working directory on a stack, then optionally change directory.

push /harddisk
push subdir
push

With a path, the current directory is pushed onto the stack and then changed to the given location.
Without a path, the current directory is swapped with the most recently pushed directory.
The stack grows as you use push, allowing you to return to earlier locations.

pop

Restore the most recently saved directory from the stack.

pop

Changes the current directory to the last one saved with push.
Removes that entry from the stack.
If the stack is empty, no change occurs.

dirs

Shows all directories pushed to the stack with push and pop

dirs

which

Show which program will be executed for any given command using PATH$ to resolve it. PATH$ is walked from left to right.

which edit

history

Show all commands stored in the command history, which you may retrieve with the cursor keys.

history

Rocketsh Variables

The rocketsh shell allows you to change certain variables that influence how the shell operates. These are:

PATH$

The PATH$ variable is a list of directories that are searched for programs to run them. Each path in PATH$ (separated by semicolons, ';') is prepended to the command line to try and match a file. If a match is found by prepending this search path, the program is executed. So for example if your program is located at /programs/tasks/foo and you type tasks/foo, with the path containing /programs, the program will be found and ran. Note this is slightly different from how paths operate in other operating systems. The current directory cannot be included in the path as it has no direct representation.

If you want to run a program that is not in the path, you must provide the full path to the program from the file system root.

LIB$

This is the path where system libraries may be found. There can be only one active library path. Programs may optionally use this global variable when loading their libraries, but it is not mandatory to do so, for example if a program wishes to load its own libraries from some non-standard location.

PROMPT$

Changing the PROMPT$ variable changes the displayed prompt of the shell to whatever you want. By default, PROMPT$ has the value "ROCKETSH". Changing PROMPT$ to an empty string will cause it to display just >, like the BBC Micro.

CSD$

You should not directly change the CSD$ variable. This shows the CSD, or 'Currently Selected Directory'.