EX

Syntax EX file *[,{filex | #chx}]* [;cmd$]
Location Toolkit II, THOR XVI

This command forces the given file (which must be an executable program) to be executed and control is then generally returned to the calling program to enable the new job to multitask alongside the calling program. Similar parameters as for EW can be passed to the job.

Use EW if the program cannot multitask for some reason or if you do not want it to, for example, because you want to see any error messages returned by the executable task. EX doesn’t report them, it cannot as the executable task may still be running when EX returns to the command prompt.

Example 1

EX QED;"readme_txt"

The QED editor will be started from the default program device and told to load the file readme_txt from the editor’s default device.

Example 2

EX UC_obj,ram1_hope_lis,par

A program called UC_obj (a program which converts text to all upper case) will be started up to run alongside all other programs. Two n:ref:ew channels (‘ram1_hope_lis’ and ‘par’) are opened for the task to use for its input and output channels respectively - the task must not open its own channels but will rely upon the user supplying them as parameters.

The BASIC version of such a program is:

110 REPeat loop
120 IF EOF(#0) THEN EXIT loop
130 INPUT #0,a$
140 IF a$='' THEN NEXT loop
150 FOR i=1 TO LEN(a$)
160   IF CODE(a$(i))>96 AND CODE(a$(i))<123 THEN
170     a$(i)=CHR$(CODE(a$(i))-32)
180   END IF
190 END FOR i
200 PRINT#1,a$
210 END REPeat loop

Turbo users will need to alter #0 and #1 to #15 and #14 respectively.

Minerva and SMS users can use this program without compiling it (see EW above).

Using EX to set up filters

It is actually quite simple to create a multitasking environment on the QL using the EX command to set up several programs all of which will process a given file (or data entered into a given channel) in turn.

The syntax for this version of the command is:

EX jobparams1*[TO jobparamsi]* [TO #chan0]

where jobparams represents the same parameters as are available for the normal EX command, being:

file *[,{filex |#chx}]* [;cmd$]

What this actually does, is to set up a chain of jobs or channels whereby one extra channel is opened for each job to form the output channel for the job on the left of the TO and another channel is opened to form the input channel of the job on the right of the TO.

Where a channel number appears at the end of the line (after a TO), this is taken as being the final output channel and nothing further can be done to the original input.

Examples

How about extending the Upper case conversion ‘filter’ so that a given text file is then printed out one line at a time with each line being printed out as normal, but then printed again, but this time backwards!

First of all, the program to do the printing:

110 REPeat loop
120   IF EOF(#0): EXIT loop: REMark Turbo uses #15, not #0
130   INPUT #0,a$:PRINT#1,a$: REMark Turbo uses #14, not #1
140   IF CMD$=='y': REMark Turbo users use OPTION_CMD$
150   IF a$='':NEXT loop
160   FOR lop=LEN(a$) TO 1 STEP -1
170     PRINT#1,a$(lop);
180   END FOR lop
190   PRINT#1
200   END IF
210 END REPeat loop

Compile this program and save the compiled version as flp1_Back_obj.

Now to carry out the desired task:

OPEN #3,con
EX flp1_uc_obj,flp1_test_txt TO flp1_back_obj,#3;'y'

On Minerva v1.93+, you could use:

OPEN #3,con
EX pipep,flp1_test_txt;'flp1_uc_bas>' TO pipep,#3;'flp1_back_bas>y'

Or on SMS:

OPEN #3,con
EX flp1_uc_bas,flp1_test_txt TO flp1_back_bas,#3;'y'

How about trying this:

OPEN #3,con
EX flp1_uc_obj,flp1_test_txt TO flp1_back_obj;'y' TO flp1_back_obj,#3;'y'

NOTE 1

On pre JS ROMs, you may find that if you EX a new Job whilst there is already one Job in progress, the ink and paper colours of the first Job are set to zero. This is a problem unless you have a key to redraw the screen for the first Job (or the Pointer Interface).

NOTE 2

The THOR XVI always ensures that cursor control is passed to the new Job on start-up rather than returning to the calling Job.

MINERVA NOTE

Please refer to notes about EW which explain how to use this command to control MultiBASICs.

SMS NOTE

Please refer to notes about EW and use this command to control multiple SBASICs.

CROSS-REFERENCE

Use FTYP or FILE_TYPE to check if a file is executable. FDAT returns the dataspace of an executable file, FXTRA provides other information. ET is very similar to EX.