builtin - HACKT CHPSIM Manual
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### 3.1 `builtin` commands

Built-in commands pertain to the interpreter, and have no relation to simulation.

— Command: help cmd

> Help on command or category cmd. ``help all`' gives a list of all commands available in all categories. ``help help`' tells you how to use `help`.

— Command: # ...
— Command: comment ...

> Whole line comment, ignored by interpreter.

— Command: echo output

> Print output to stdout. Note: multiple spaces in output are compacted into single spaces by the interpreter's tokenizer.

— Command: exit
— Command: quit

> Exit the simulator.

— Command: abort

> Exit the simulator with a fatal (non-zero) exit status.

— Command: repeat n cmd...

> Repeat a command cmd a fixed number of times, n. If there are any errors in during command processing, the loop will terminate early with a diagnostic message.

— Command: interpret

> Open an interactive subshell of the interpreter, by re-opening the standard input stream. This is useful when you want to break in the middle of a non-interactive script and let the user take control temporarily before returning control back to the script. `Ctrl-D` sends the EOF signal to exit the current interactive level of input and return control to the parent.

— Command: ! shell-cmd

> Shell escape. Execute shell-cmd in parent shell, like the ``system`' library function, e.g. ``!date`'. Note: this preserves the rest of the line after the `!' verbatim.

The following commands are related to command aliases. Every command line given to the interpreter recursively expands the first token if it has a known alias. Aliases may reference to other aliases in the first token. The interpreter is smart enough to catch cyclic aliases and report an error.

— Command: alias cmd args

> Defines an alias, whereby the interpreter expands cmd into args before interpreting the command. args may consist of multiple tokens. This is useful for shortening common commands.

— Command: aliases

> Print a list of all known aliases registered with the interpreter.

— Command: unalias cmd

> Undefines an existing alias cmd.

— Command: unaliasall

> Undefines all aliases.

The following command is useful for showing each executed command.

— Command: echo-commands arg

> Enables or disables echoing of each interpreted command and tracing through sourced script files. arg is either "on" or "off". Default off.