Updated June 2022; see History
Certain special commands or tokens begin with the colon, which may be in the first column or which can be indented.
|
Command |
Meaning |
|
:< .... > |
outputs the text between the opening and closing angle brackets; may span multiple lines. This is the normal way to print operational messages on the screen from within command files. |
|
:T |
causes all commands from that point forward to be traced—i.e., be displayed on the screen. This is very useful for debugging, but may be too verbose for normal use. |
|
:R |
causes just the output of commands to be displayed; the commands themselves do not display. This produces a somewhat cleaner looking result. |
|
:S |
silences all output. Unfortunately, this is the default, if neither :t or :r are supplied first. |
|
:X (exit) |
causes the CMD or DO file to exit. This is equivalent to the EXIT command. |
|
|
stops and waits for keyboard input. The input is then processed by whatever process is currently in effect (i.e. either a program or the command line processor itself). For example: SET
CTRLC |
|
|
may be used in conjunction with :k to append the keyboard input to a partial command line. For example: :R |
The command file processor supports a variation of the :K token to input keyboard responses into variables which can tested in IF statements and used as DO file parameters. The following sample file provides an example:
:R
:<Enter desired ppn: >
:K0
:S
:<Enter password: >
:K9
IF "$KBD9" = "SECRET"
DOLOG $KBD0
The special token :K0 is like :K, in that it waits for a line of input, but instead of passing the input to the current program, it simply stores it as $KBD0. The same concept applies to :K1 thru :K2 ($KBD1 thru $KBD9). The special $KBDn variables may be tested in an IF statement or passed as a command line argument to a DO file.
Note that when using $KBDn in an IF statement, it must be quoted as in the example above. However, when using it as a DO file command argument, it should not be quoted. In the example above, the DO file dolog.do will see the $KBD0 on its command line and convert it to whatever had been entered to the "Enter desired ppn" prompt.
$KBDn variables cannot be used in any other context, even within a command file. Unlike other special $xx variables which can appear in DO files, which are expanded by DO.LIT when it loads the DO file, the $KBD variables cannot be expanded until after the input operation takes place, and thus it is left to individual commands (just IF and DO) to interpret them.
History
June 2022: A-Shell 6.5.1715, DO.LIT 2.1(126): support indentation of the colon directives as illustrated in the example MAIN.DO; previously they had to be in column 1.
December 2004, A-Shell 4.9.909: Function added to A-Shell