TACL Command

The use of commands is the simplest interactive use of TACL.
Predefined commands of TACL such as:

RUN                    Runs a process

STATUS              Displays information about one or more running processes

ENV and WHO    Describes your TACL environment

FUP                    To start a process, and type the program name, to invoke the program. 

User can include user-defined commands if you or your system manager define them. 

TACL Metacharacters

Square Brackets ([ ])
You can enclose var1 in square brackets to obtain the contents of var1 or you can omit the brackets to obtain the text var1:

12> #OUTPUT [var1]
3
13> #OUTPUT var1
var1

** However, when you supply a variable name as an argument to one of these commands or built-in functions (#IF #COMPUTE), you do not need to enclose a variable name in square brackets.

Tilde (~)
The tilde is used in combination with another character:

 ~; simulates an end-of-line character。
 ~_ represents a space character when #OUTFORMAT is set to PRETTY.
 TACL replaces the combination of a tilde and a metacharacter with the metacharacter itself. For example, ~[ becomes [, and ~== becomes ==.
 TACL replaces the combination of a tilde and a character that is not a metacharacter with a single question mark. For example, ~A becomes ?

Question Mark (?)
TACL uses the question mark character for two purposes:

- Displaying previous command lines
- Specifying the start of a TACL directive

To start a line with a question mark for any other purpose, use two question marks. TACL then discards the first question mark and any adjacent spaces and treats the remainder of the line as text.