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This is about the AS/400 which is an IBM mini-computer launched in 1988. It lives on today after several name changes and considerable hardware and software changes. It is still often informally called the AS/400 but this is about the early days when that was still the official name. OS/400 was its operating system and the two were tied to each other.

I read, back in the 1990s, that there was a special system program which if deleted would trigger the O/S to uninstall itself during the next IPL (boot). The idea was that an IBM engineer could delete this program if they detected that the system was unlicensed. I think that I read this in an official, reliable source but I cannot be sure after so long. I have been unable to find confirmation. Certainly, IBM took the licensing issue seriously and I am aware of several serious disputes but not the use of this nuclear option.

Can anyone confirm this as true?

Can anyone confirm it as an urban myth that I fell for?

badjohn
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    Don't know about AS/400 but on MS DOS, if you deleted . (dot) from the C: drive, it wiped the entire disk including OS. – cup Apr 14 '21 at 15:25
  • @cup I guess that on many old systems (and maybe new ones as well) you can easily sabotage the system with various deletions. The interesting thing here (if my memory was correct) is that the purpose of this program was to trigger the uninstall. It would not be immediate but at the next IPL (boot). – badjohn Apr 14 '21 at 15:28
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    Just curious - I know it’s IBM, but how could a system be “unlicensed”? I didn’t think you could run OS/400 on non-IBM hardware, or buy an AS/400 without OS/400. Was it an annual fee for the OS or maintenance/support fee rather than a perpetual license? Or running an updated version when you didn’t pay maintenance? – mannaggia Apr 14 '21 at 16:58
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    @cup That is not true. I was sceptical and tried it on fresh MS-DOS 6.22 install. On root of C: drive, executing "del ." would first of all ask if you are sure, and all it does it deletes non-hidden non-system files, so it only deletes CONFIG.SYS and AUTOEXEC.BAT. All subdirectories such as DOS and important OS files are still present (IO.SYS, MSDOS.SYS and COMMAND.COM) on drive root. Would you specify which version of MS-DOS does wipe entire disk? – Justme Apr 14 '21 at 17:11
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    @mannaggia I can't remember the exact details but it might be that buying second hand hardware does not entitle you to the operating system. Certainly, somehow you could get into an illegimste state. – badjohn Apr 14 '21 at 20:47
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    @mannaggia - IBM software was leased. Monthly fee. IIRC. The hardware too of course - that was the subject of an action brought by the US government because IBM refused to sell the hardware. But the software too I'm pretty sure (though wikipedia doesn't mention it). – davidbak Apr 15 '21 at 00:59
  • @justme I've never tried it but my brother-in-law did on DOS 3.0. He knew he hadn't created the files called . or .. so he deleted them both and the whole OS disappeared. – cup Apr 15 '21 at 06:19
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    @cup Oh and the root of drive would not have "." and ".." either. They are the names or links for current and previous directory. But it is true that DOS 3 did not protect the command interpreter so it is possible to delete COMMAND.COM, but still, typing "del ." on C: drive root would delete COMMAND.COM and any other files not protected like CONFIG. SYS and AUTOEXEC.BAT. It would not "wipe the entire disk" or cause the whole OS to "disappear". But yes the system is unusable until booted from DOS floppy, in which case command interpreter can be copied back to hard drive. – Justme Apr 15 '21 at 08:34
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    This DOS discussion is interesting but probably deserves its own question as it is completely unrelated to OS/400. Today, the descendant of OS/400 has a hierarchical Unix like file system but at the time of this question, it did not. It was very, very different from DOS. – badjohn Apr 15 '21 at 08:51
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    Check this out: http://www.snee.com/bob/opsys/part4os400.pdf – HackSlash Aug 10 '22 at 15:50
  • Thanks. I have just glanced so far but it looks good. I don't know yet whether it answers my question but it is certainly interesting. – badjohn Aug 11 '22 at 07:18
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    @badjohn AS/400 and the later System i has a functionality to run unaltered AIX executables but the database inspired filesystem with its language CL is very much still available. Though their nowadays is with python/bash/rpm available. – Stefan Skoglund Sep 05 '22 at 23:35
  • @StefanSkoglund I know, I still use it every day (well, every working day). – badjohn Sep 06 '22 at 04:48
  • I imagine that, assuming you have permissions, clearing out all the contents of the QSYS library would render the OS unusable, which could be functionally equivalent to "uninstalled" :-) – paxdiablo Dec 30 '22 at 05:59
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    @paxdiablo Probably so but the question was not about how to destroy the O/S in any manner. There are probably many ways to do that. The question was about a program whose purpose was to trigger a delayed uninstall. One accidental near destruction that I witnessed was someone who thought that taking away all authority for all users for all objects would be a good first step strict security. It rendered the system unable to IPL and it took IBM engineers days to recover the system. – badjohn Dec 30 '22 at 11:53
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    Wouldn't be surprised if the IBM field engineers demanded such a thing to give them time to get out of the building before the irate VP of Information Systems came down to beat them with heavy cudgels. – davidbak Aug 07 '23 at 22:01
  • @mannaggia Enterprise systems and software are licensed with many twists. For example, some sales/CRM/accounting software is licensed via a percentage royalty of the sales processed. IBM commonly sells software and hardware as a backup for disaster recovery very cheaply; it is illegal to use it except for tests and when the primary system fails. A system may be sold cheaply for development, and no actual customer workloads are allowed. In cases like these only an audit could determine whether they were complying with license terms. – user71659 Aug 08 '23 at 04:54
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    I only can confirm that it is a strong one, true or myth, the story has been around for as long as I can remember the AS/400 existed. – ABM K Aug 21 '23 at 16:02
  • @ABMK Do you remember the story? If so then it is progress, it means that I didn't dream it up. Of course, we still wouldn't know whether it was true. – badjohn Aug 21 '23 at 20:23
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    @badjohn Oh yes, I remember the story. But nothing more than that. I don’t remember where I first read it, and certainly not if it was true. Let’s say that if I would have tested it on the only AS/400 I ever had ALLOBJ SECADM on, the company would have killed me on the spot :) – ABM K Aug 22 '23 at 11:30

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I once had a PTF (program temporary fix) take down the entire system. After a day or so of applying what looked like a simple fix, it triggered an IPL (Initial Program Load). The system got stuck in a loop and wouldn't load from any source. An engineer attended and recovered the System with an IPL type C. It took around 7 hours to recover.

see > IPL Types

Dach
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  • Thanks but the question is not about anyway to break tye system or how it might itself but a mythical program whose purpose was to trigger an uninstall. – badjohn Aug 07 '23 at 20:53
  • The OS is protected (sitting above the subsystems). I can't see how any program could access that. We IPL to a different bank to install PTFs, once happy (days/weeks later) we apply the PTFs permanently and switch to the other bank. I can't imagine a way for a program to automatically gain access to both OS banks and delete the OS, it requires human intervention and access to the control panel. I'm sure this is why IBM designed the two OS banks (three if we count bank C) to protect from utter disaster. – Dach Aug 07 '23 at 22:41
  • If you delete enough licenced programs (GO LICPGM) this will screw things up nicely, programs will not be able to gain access to resources they need. However the basic OS will still be running so this doesn't do 100% what you are looking for. The Admin will IPL to A to recover from this. – Dach Aug 07 '23 at 22:53
  • The story is old and the system was much simpler then. Also, as an IBM program, it could potentially do almost anything. – badjohn Aug 07 '23 at 23:13
  • As I said, I am not trying to find out how to sabotage the system. I am trying to confirm or deny the story that IBM themselves put in this self-destruct switch. I know someone who came very close to destroying the system without deleting anything: he merely removed all authority to all objects from all users. It took days for IBM to sort out the mess. – badjohn Aug 07 '23 at 23:15
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    I've never personally heard about a program that can do that. I spent 32 years working on IBM mainframes, System 36 / 38 / AS400, iseries. Programmer to System manager. Many long nights sat with IBM engineers listening to their stories. – Dach Aug 08 '23 at 02:19
  • I have similar experience. I also worked with the S/38 and I got to play with the AS/400 before launch. My memory is that I saw this in writing but it is so long ago and so hard to verify that I doubt my own memory, hence this question. – badjohn Aug 08 '23 at 07:06