Deadly Embrace on Login Screen

[ajax]

I attempted to mount another file-system (partition) on /tmp. The idea being to separate the storage used for temporary files from the rest of my system. To me temporary files mean those that need not be saved and that the system is not dependent on. However, my experience suggests that there is something going on, possibly pertaining to kdm, that violates this premise.

When I changed /etc/fstab to mount a secondary file-system the system booted up as usual and presented the logon screen. However, when I enter the password the result is that the screen goes blank momentarily and then re-displays the same logon screen. This continues indefinitely. I'm inclined to think that the new file-system mounted at /tmp contains no less information than it did the first time I logged onto my system. Furthermore, by hot-keying out of X-Windows and obtaining a conventional console I was able to logon and verify that the new file-system was properly mounted and in fact some files had been stored there as a result of trying to start the system. Then by restarting the system with the former version of /etc/fstab I was able to resume normal operation. I couldn't find any helpful clues in either /var/log/messages or /var/log/syslog.

An obvious work-around would be to transfer the few files that exist in the working /tmp directory to the new file-system and try again. However, such a dart throwing approach doesn't fit with my intention which is to use this same secondary file-system for multiple systems. Therefore I think it is important that my premise regrading temporary files is valid and that any subsystem dependencies are corrected.

It doesn't seem like what I'm trying to do is so unusual and even though I don't have any good troubleshooting clues my inclination is to suspect that there must be something about X11, kdm, etc. that I've failed to recognize.

Can anyone explain what is going on here? I'd be most grateful for some help.

[tinker]

Re: Deadly Embrace on Login Screen

I attempted to mount another file-system (partition) on /tmp. The idea being to separate the storage used for temporary files from the rest of my system. To me temporary files mean those that need not be saved and that the system is not dependent on. However, my experience suggests that there is something going on, possibly pertaining to kdm, that violates this premise.

I think those temp files are cleared on boot anyway, aren't they?

When I changed /etc/fstab to mount a secondary file-system the system booted up as usual and presented the logon screen. However, when I enter the password the result is that the screen goes blank momentarily and then re-displays the same logon screen. This continues indefinitely. I'm inclined to think that the new file-system mounted at /tmp contains no less information than it did the first time I logged onto my system. Furthermore, by hot-keying out of X-Windows and obtaining a conventional console I was able to logon and verify that the new file-system was properly mounted and in fact some files had been stored there as a result of trying to start the system. Then by restarting the system with the former version of /etc/fstab I was able to resume normal operation. I couldn't find any helpful clues in either /var/log/messages or /var/log/syslog.

The symptoms you describe might suggest that the system couldn't start X for the user. Have you checked the user's home for .xsession-errors?

An obvious work-around would be to transfer the few files that exist in the working /tmp directory to the new file-system and try again. However, such a dart throwing approach doesn't fit with my intention which is to use this same secondary file-system for multiple systems. Therefore I think it is important that my premise regrading temporary files is valid and that any subsystem dependencies are corrected.

I don't consider that a dart throwing exercise, it might give you more data. If by doing so your system worked the way you want it to then you might have a better idea what to inspect next. But, each person has their own style of troubleshooting.

It doesn't seem like what I'm trying to do is so unusual and even though I don't have any good troubleshooting clues my inclination is to suspect that there must be something about X11, kdm, etc. that I've failed to recognize.

It seems unusual to me, but GNU/Linux we have choice. If you have a need to use it that way, it doesn't matter what I think about it.

[dibl]

Re: Deadly Embrace on Login Screen

I attempted to mount another file-system (partition) on /tmp. The idea being to separate the storage used for temporary files from the rest of my system. To me temporary files mean those that need not be saved and that the system is not dependent on. However, my experience suggests that there is something going on, possibly pertaining to kdm, that violates this premise.

That could work if by "temporary" you also mean "disappears at next shutdown". I'm not an expert on what is loaded by the system in /tmp at startup, but I do know that it is NOT the stuff that you left there last booted session. I often use it for installing packages and drivers, when I don't intend for the source packages to be hanging around after the next shutdown.

When I changed /etc/fstab to mount a secondary file-system the system booted up as usual and presented the logon screen. However, when I enter the password the result is that the screen goes blank momentarily and then re-displays the same logon screen. This continues indefinitely.

We call this "login loop" -- it is a known phenomenon, with several different causes. A search of the forum will show threads going back several years. Mis-mounted and full filesystems are known causes of it, for example.

It doesn't seem like what I'm trying to do is so unusual and even though I don't have any good troubleshooting clues my inclination is to suspect that there must be something about X11, kdm, etc. that I've failed to recognize.

Can anyone explain what is going on here? I'd be most grateful for some help.

Since you've already confessed to a certain predisposition to editing /etc/fstab, why not just make a mount point in /media for this project? It will only cost you a few bytes of disk space. Then mount your other filesystem on it for as long as needed, and skip the fight with /tmp.

[ajax]

Re: Deadly Embrace on Login Screen

Well now I'm a bit embarrassed to reveal what I found but it looks to be as simple as making sure that the user who is logging on is permitted to create files in the root directory of the secondary file-system. When mounting it as /tmp it might be best to insure that this directory is world writable. What needs remembering is that you have to do this before you try to boot the system using it as /tmp.

The reason for wanting to mount a secondary file-system as /tmp and not just any old mount point is that I don't want the temporary files created by many different programs and mostly unbeknown to me to occupy space in the partition images that I create for the purpose of recovering the system (primarily software). My experience with Ubuntu/Linux is sufficiently limited that I cannot say how big a deal it is but I can tell you from considerable experience that on Windows it is a really big deal. I use a similar approach for the files that I produce as a result of my work which are also backed up differently depending on their purpose. However, this can use a mount point of my own making and didn't have any impact on booting the system.

[tinker]

Re: Deadly Embrace on Login Screen

Ajax,
A person in your situation, knowledgeable about the Redmond operating system but new at GNU/Linux often has a few problems like this until they become familiar with the differences. One thing you learned this time is about permissions, and it would serve you well to continue to learn more about them. For another example, you might eventually need to discover that an executable file needs to be marked as such, because that isn't determined by file extension, like in Windows. There are lots of differences and it isn't always productive or best to try and make a Linux operating system conform to the form and mindset that one brings from other experience.

There are reasons that the developers have chosen to set certain permissions in certain places. I'm not sure that the way you have chosen to use /tmp is going to operate as you expect or give you the results you desire, it might, but it also might not. It is not the "big deal" that it is in Windows. The Linux Filesystem Hierarchy, is setup the way it is for a reason, you might want to have a read through:
http://tldp.org/LDP/Linux-Filesystem...tml/index.html

You might also want to become more familiar with mounting, if what you are worried about is the system writing to partitions that you have as backup, no programs are going to write anything, temporary or otherwise, to an unmounted partition. An unmounted partition is pretty safe unless the physical drive crashes or you make some mistake with a partitioning tool. Thus your backups would be safe and clean.

You caught the difference that makes a multi-user operating system safe for each user's files. Only the user and the admin (root or a user with some or all root permissions) can muck with files that they did not create. That's simplified, because I can't sit here and type out a course on Linux, but you do have some keywords and one link to get started.

Another thing you will probably want to do is learn is that one can access the manual page for a command by entering "man command" (without the quotes) in a terminal. For example, man mount, will show the manual for the mount command.

There will be lots to learn, someone like yourself who is interested, will probably have fun doing it. There might even be some "aha!" or "wow!" moments as you are discovering the value and beauty of open source software.