Amiga questions you've always been too embarrassed to ask - Page 109

jizmo · 11 May 2019, 13:26

Given that Amiga multitasks by default, why do most Amiga programs completely halt command lines unless executed with a 'RUN' command?

NLS · 11 May 2019, 13:36

Why is one related to the other?
The "process" opened by the specific window is used by the command.
For a program to open a new process is the dev's choice (and not something enforced by Commodore guidelines IIRC).
As you already said using "run" is enough, or opening a new shell before running something in the first.

A multi-tasking OS doesn't mean the shell is multi-tasking. You can have many, or explicitly send commands to other process. It also has to do with the I/O. If a command needs to "capture" the I/O (without opening a window), it is much cleaner to just use own shell's I/O.
Linux is multi-tasking and is the same. Many commands take over the shell and you need to explicitly push them in the background.

daxb · 11 May 2019, 13:42

It depends, I think. If you want serialisation or parallelisation. In scripts for example normally you want to wait for a command finished or get the result. If you are in the Shell and type commands you can choose (run or not) what you prefer.

Daedalus · 11 May 2019, 19:09

It's pretty reasonable for a command to halt the shell by default. After all, what good is being able to run a second command when the previous command is listing off its output? And would you want the two output streams mixed together? Or leave the second one until the first is finished? You can already enter another command while the first one is running, and it will be executed as soon as the first one is finished. So you can queue up commands without needing to write a script.

jizmo · 11 May 2019, 23:53

I guess I did not word my question right. The shell running multiple programs outputting text would not obviously make much sense.

I was referring to using command line to launching non-cli programs that open up in separate windows or screens: Sometimes they release the shell right after the program has opened, but more often the shell is locked until the user exits the program, effectively meaning one should always execute them using a 'RUN' command just to be on the safe side.

If the program does not use the command line, but open up in a window instead, why does it need to halt the CLI by default? And how do some programs prevent this, do they send some exit flag to the shell after they've started up?

MartinW · 11 May 2019, 23:58

It isn't really halting anything. The shell starts a second process which is spawned by the process in which the shell is running. That's busy until such time as the GUI based software has finished so the shell appears to be locked. It's not really, it just hasn't finished the task you asked it to do. Hence, if you "run" the new process you're detaching from the original process.

I'm probably not explaining myself well

Daedalus · 12 May 2019, 00:27

Yeah, that's the default because, at the time of launching, the Shell doesn't know whether it's a program that needs to output text to the Shell window or not. You're right, of course, that a program shouldn't need to tie up the Shell like that if it doesn't need to, but that's not a decision the Shell can make - after all, there are programs out there that have a GUI while also outputting to the console window.

It's up to the program to detach itself from the Shell, which is possible but is extra code. I guess most programmers simply aren't bothered enough to add that functionality, especially if they mainly intended their program to be run from the Workbench anyway.

jizmo · 12 May 2019, 08:17

Thanks for the answers – I've been always wondering why this behaviour was so random.

Sounds like it could've been fixed with some sort of file flag that tells the program to detach itself from Shell if run from there. But I guess us command line users were never a high priority for Commodore for whom CLI existed mostly to just run the scripts.

NLS · 12 May 2019, 17:32

Well that's a bit unfair for Commodore and CLI.
It works as intended - then programmers needed to abide and didn't always.
CLI when first released was way better than the then version of MS-DOS and much closer to UNIX (sans-multi-user).

Thomas Richter · 12 May 2019, 20:51

Quote:

Originally Posted by jizmo

If the program does not use the command line, but open up in a window instead, why does it need to halt the CLI by default? And how do some programs prevent this, do they send some exit flag to the shell after they've started up?

The answer is as simple as it could be: Because without taking any other action, this is how the shell and the workbench behave. A program needs to include additional logic to detach from shell. Otherwise, the program "overloads" the shell process, until it returns to the shell.

The workbench, however, detaches programs by itself - unlike the shell, which runs programs as part of its own process.

Predseda · 12 May 2019, 20:54

Q: What the NIL: stands for? Is it an abbreviation?

kolla · 12 May 2019, 21:03

https://en.wikipedia.org/wiki/0

Amiga/TRIPOS NIL: is equivalent to unix /dev/null, a device that swallows anything you send to it.

zipper · 12 May 2019, 21:34

Originally from Latin. Nil = nothing, zero.

NLS · 13 May 2019, 16:32

Nil = null

EugeneNine · 13 May 2019, 19:10

Quote:

Originally Posted by jizmo

I guess I did not word my question right. The shell running multiple programs outputting text would not obviously make much sense.

I was referring to using command line to launching non-cli programs that open up in separate windows or screens: Sometimes they release the shell right after the program has opened, but more often the shell is locked until the user exits the program, effectively meaning one should always execute them using a 'RUN' command just to be on the safe side.

If the program does not use the command line, but open up in a window instead, why does it need to halt the CLI by default? And how do some programs prevent this, do they send some exit flag to the shell after they've started up?

It only halts that instance of the CLI, you can open additional CLI's to run other programs in those instances.
I bet the reason some gui programs let the cli you launched them from is because they installed a simple script that 'RUN's them. The default behavior is that program runs in that cli (and therefore takes it over) unless you tell it to run separate via a 'RUN' (or & in Li/Unix)

EugeneNine · 13 May 2019, 19:42

So my search-fu apparently is weak, is there a serial number decoder anywhere that maybe tells things like date built, etc?

slaapliedje · 14 May 2019, 03:22

Quote:

Originally Posted by EugeneNine

So my search-fu apparently is weak, is there a serial number decoder anywhere that maybe tells things like date built, etc?

Pretty sure there is one for most Atari systems. Thought there might be for the Amiga. Usually it was based on the week of the year and batch number for some Atari systems.

I will follow with a new question. Does anyone else's AmigaOS 4.1 FE for Classic make your CDROM sound like it is trying to turn a vinyl album into afloppy drive? It just starts to make mine scream. No other disks I have put in it does that.

Estrayk · 16 May 2019, 16:12

QUESTION:

I have always wondered how it is possible that the old photogenics could manipulate HAM8 images without HAM-artifacts. What kind of witchcraft was that?

Video from my real Amiga A1200:

[ Show youtube player ]

NLS · 16 May 2019, 16:32

Is it HAM? Or is 256 color mode?

(also IIRC HAM8 produces less distinct artifacts than HAM6)

Estrayk · 16 May 2019, 23:08

Quote:

Originally Posted by nls

is it ham? Or is 256 color mode?

ham8

11 May 2019, 23:53	#2165
jizmo Registered Abuser Join Date: Oct 2013 Location: Valencia / Spain Posts: 361	I guess I did not word my question right. The shell running multiple programs outputting text would not obviously make much sense. I was referring to using command line to launching non-cli programs that open up in separate windows or screens: Sometimes they release the shell right after the program has opened, but more often the shell is locked until the user exits the program, effectively meaning one should always execute them using a 'RUN' command just to be on the safe side. If the program does not use the command line, but open up in a window instead, why does it need to halt the CLI by default? And how do some programs prevent this, do they send some exit flag to the shell after they've started up? Last edited by jizmo; 11 May 2019 at 23:58.

12 May 2019, 08:17	#2168
jizmo Registered Abuser Join Date: Oct 2013 Location: Valencia / Spain Posts: 361	Thanks for the answers – I've been always wondering why this behaviour was so random. Sounds like it could've been fixed with some sort of file flag that tells the program to detach itself from Shell if run from there. But I guess us command line users were never a high priority for Commodore for whom CLI existed mostly to just run the scripts. Last edited by jizmo; 12 May 2019 at 08:34.

12 May 2019, 21:03	#2172
kolla Banned Join Date: Nov 2007 Location: Trondheim, Norway Posts: 1,893	Amiga questions you've always been too embarrassed to ask https://en.wikipedia.org/wiki/0 Amiga/TRIPOS NIL: is equivalent to unix /dev/null, a device that swallows anything you send to it.

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11 May 2019, 13:26	#2161
jizmo Registered Abuser Join Date: Oct 2013 Location: Valencia / Spain Posts: 361	Given that Amiga multitasks by default, why do most Amiga programs completely halt command lines unless executed with a 'RUN' command?

11 May 2019, 13:36	#2162
NLS Ancient User Join Date: Apr 2007 Location: GREECE Age: 50 Posts: 757	Why is one related to the other? The "process" opened by the specific window is used by the command. For a program to open a new process is the dev's choice (and not something enforced by Commodore guidelines IIRC). As you already said using "run" is enough, or opening a new shell before running something in the first. A multi-tasking OS doesn't mean the shell is multi-tasking. You can have many, or explicitly send commands to other process. It also has to do with the I/O. If a command needs to "capture" the I/O (without opening a window), it is much cleaner to just use own shell's I/O. Linux is multi-tasking and is the same. Many commands take over the shell and you need to explicitly push them in the background.

11 May 2019, 13:42	#2163
daxb Registered User Join Date: Oct 2009 Location: Germany Posts: 3,303	It depends, I think. If you want serialisation or parallelisation. In scripts for example normally you want to wait for a command finished or get the result. If you are in the Shell and type commands you can choose (run or not) what you prefer.

11 May 2019, 19:09	#2164
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	It's pretty reasonable for a command to halt the shell by default. After all, what good is being able to run a second command when the previous command is listing off its output? And would you want the two output streams mixed together? Or leave the second one until the first is finished? You can already enter another command while the first one is running, and it will be executed as soon as the first one is finished. So you can queue up commands without needing to write a script.

11 May 2019, 23:58	#2166
MartinW Registered User Join Date: Mar 2017 Location: Minehead / UK Posts: 608	It isn't really halting anything. The shell starts a second process which is spawned by the process in which the shell is running. That's busy until such time as the GUI based software has finished so the shell appears to be locked. It's not really, it just hasn't finished the task you asked it to do. Hence, if you "run" the new process you're detaching from the original process. I'm probably not explaining myself well

12 May 2019, 00:27	#2167
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Yeah, that's the default because, at the time of launching, the Shell doesn't know whether it's a program that needs to output text to the Shell window or not. You're right, of course, that a program shouldn't need to tie up the Shell like that if it doesn't need to, but that's not a decision the Shell can make - after all, there are programs out there that have a GUI while also outputting to the console window. It's up to the program to detach itself from the Shell, which is possible but is extra code. I guess most programmers simply aren't bothered enough to add that functionality, especially if they mainly intended their program to be run from the Workbench anyway.

12 May 2019, 17:32	#2169
NLS Ancient User Join Date: Apr 2007 Location: GREECE Age: 50 Posts: 757	Well that's a bit unfair for Commodore and CLI. It works as intended - then programmers needed to abide and didn't always. CLI when first released was way better than the then version of MS-DOS and much closer to UNIX (sans-multi-user).

12 May 2019, 20:54	#2171
Predseda Puttymoon inhabitant Join Date: Mar 2007 Location: Tromaville Age: 46 Posts: 7,539	Q: What the NIL: stands for? Is it an abbreviation?

12 May 2019, 21:34	#2173
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,837	Originally from Latin. Nil = nothing, zero.

13 May 2019, 16:32	#2174
NLS Ancient User Join Date: Apr 2007 Location: GREECE Age: 50 Posts: 757	Nil = null

13 May 2019, 19:42	#2176
EugeneNine Registered User Join Date: Aug 2016 Location: Ohio Posts: 185	So my search-fu apparently is weak, is there a serial number decoder anywhere that maybe tells things like date built, etc?

16 May 2019, 16:12	#2178
Estrayk Registered User Join Date: Apr 2015 Location: Spain Posts: 511	QUESTION: I have always wondered how it is possible that the old photogenics could manipulate HAM8 images without HAM-artifacts. What kind of witchcraft was that? Video from my real Amiga A1200: [ Show youtube player ]

16 May 2019, 16:32	#2179
NLS Ancient User Join Date: Apr 2007 Location: GREECE Age: 50 Posts: 757	Is it HAM? Or is 256 color mode? (also IIRC HAM8 produces less distinct artifacts than HAM6)

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