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InvsbleChuck · Post by **InvsbleChuck** » Tue Mar 04, 2003 4:28 am

I know this is probably a bash problem, but I've never experienced it under any other distro but gentoo.

If I'm on console 1 with a process running and generating output and switch to console 2 and then switch back, I cannot scroll up to see the output that occured while i was away. Also when I don't switch away the buffer seems really small.

How do I change this? Again I realize that this is not a problem with gentoo, per se, but probably a setting that is different from what I'm used to.

TIA

Carlos · Post by **Carlos** » Tue Mar 04, 2003 12:18 pm

This is actually a fundamental limitation of the virtual console, and from what I recall there's no solution (that is, short of going into the code yourself).

alec · Post by **alec** » Tue Mar 04, 2003 12:25 pm

Try screen - it keeps more in the buffer so you can scroll back eve when switching consoles.

InvsbleChuck · Post by **InvsbleChuck** » Wed Mar 05, 2003 1:05 am

Thanks Carlos & alex.

Funny I don't remember this ever being a problem before. I remember at least being able to switch consoles and scroll back. Is this something new to the 2.4 kernels.

Weird!

EDIT: Sorry alec, I realized i spelled your name wrong after the post!!!

tgoodaire · Post by **tgoodaire** » Wed Mar 05, 2003 1:37 am

I'm having the same problem. I didn't have this problem with Mandrake, Debian, or Linux from Scratch (all using 2.4 kernels).

I don't know what it could be. Termcap, inputrc, readline, gettext, bash? It seems to me that something isn't being set properly when I change terminals. It's forgetting that I have text that's scrolled off the screen.

Puzzling.

InvsbleChuck · Post by **InvsbleChuck** » Wed Mar 05, 2003 11:41 am

Ok, so I'm not crazy (at least not because of this

). I really think this is either a problem with the defaults in gentoo or something with the later series of kernels (Maybe after 2.4.5).

I'm finding this more and more annoying every day. It's not so much when I'm working on my own workstation, but when I am SSh'ed to somewhere else.

patsonrt1 · Post by **patsonrt1** » Sat May 24, 2003 2:58 am

This seemed like a appropriate place for this question

How to you adjust how many lines of scrollback you have? Presently I only get a page or 2 of scrollback. It's the same with ssh. I need more as I am to lazy to add "| more" to dmesg

Thanks for any suggestions.

InvsbleChuck · Post by **InvsbleChuck** » Sun May 25, 2003 7:05 am

I think as Carlos said above and from what I've read about it I think the only way to change it is to go into the code.

But I am really, really tempted to go back to an old distro just to see if this was a problem in the 2.2 kernels. I, for the life of me, don't remember scrollback working this way before.

GuidoJ · Post by **GuidoJ** » Sun May 25, 2003 8:05 am

As noted by Carlos this is how VC's work. There is only one scroll back buffer for all VC's, which means that is used solely for the active VC. AFAIK this is how VC's have always worked and is the same in all kernels and every distro.

In stead of a VC you can also try running stuff in an xterm or equivalent. Such terminal windows generally let you specify the number of lines that are saved in the scroll back buffer. Of course every xterm has its own scroll back buffer. Since distro's like Mandrake normally boot right into graphics mode, this is what you saw there maybe?

patsonrt1 · Post by **patsonrt1** » Sun May 25, 2003 2:22 pm

Thanks for the reply chamiltonj, I am not as concerned about switching consoles but just the scrollback for a single VC. It dosen't matter if I use a VC, Xterm or SSH they all only offer 2 pages of scollback. Is this the same issue?

InvsbleChuck · Post by **InvsbleChuck** » Sun May 25, 2003 6:13 pm

As GuidoJ mentioned, if you use xterm and SSH you can adjust the amount of scrollback. The program screen allows you to do this as well. But i found screen is a little less intuitive starting and and also using the scrollback.

I often forget to start screen before doing real work.

tom · Post by **tom** » Wed Jun 18, 2003 2:06 pm

Something I've always wondered is: How can I get 'screen' to scrollback like my usual xterms do?? Normally I just use Shift+PgUp to go through the pages, but if I'm running screen it only displays stuff from before I invoked screen.

From reading the above posts, this sounds like it might not be possible. I didn't realise that xterm, etc. actually maintained their own scrollback buffers. If not, could someone let me know how to scroll back through screen's buffer (if it has it's own?), I've never figured it out.

Plus if anyone knows of any sites with a list of tips and tricks for screen, could they please post a link. I'm sure I'm a very long way from being efficient with this little gem of a program!

Cheers,
Tom.

chemaja · Post by **chemaja** » Thu Oct 23, 2003 4:01 pm

The scrollback problem is getting to me, too.

Although I don't have the solution to this no-scrollback problem, I am 99% sure that its not the kernel, or an inherrent VC limitation. It's probably some bash variable that is set incorrectly, or not at all.

At the moment I've got too much on my TODO list to resolve the issue, but I'm sure in the next month it will irritate me enough for me to fix it.

If someone has the time, I suggest start by troubleshooting bash. If it's not bash, then it'll be something user-editable just below it. I've used a whole bunch of fairly new distros (Redhat 9, Mandrake 9.1, Debian unstable), and they don't seem to have this problem.

cripwalk · Post by **cripwalk** » Thu Oct 23, 2003 8:31 pm

I think the amount of scrollback is limited to the amount of video memory you have, so you cant increase the amount.

chemaja · Post by **chemaja** » Sat Oct 25, 2003 3:47 am

I think the amount of scrollback is limited to the amount of video memory you have, so you cant increase the amount.

if that was the case, then there should be a *bucketload* of scrollback. I've got a 16MB RIVA TNT. That's pretty small by today's standards, but its a HELL OF A LOT of plain-text storage, even if you factor in resource use by other processes.

Besides, bash doesn't talk directly to the hardware. Even if there *wasn't* enough memory, it could always use the swap partition.

cripwalk · Post by **cripwalk** » Sat Oct 25, 2003 7:22 pm

Well there must be a limit set on how much video ram the scrollback is allowed to use. Obviously it not going to use all of your video memory just for scrollback. I have 128mb of ram on my video card and I dont see a difference between that and my 16mb vid card on my other computer.

Here is an interesting link i found:
http://www.oreillynet.com/pub/faqs/linux_faq_AEN2554

Question: 8.6. How To Scroll Backwards in Text Mode.
Answer:

With the default US keymap, you can use Shift with the PgUp and PgDn keys. (The gray ones, not the ones on the numeric keypad.) With other keymaps, look in /usr/lib/keytables. You can remap the ScrollUp and ScrollDown keys to be whatever you like.

The screen program, http://vector.co.jp/vpack/browse/person/an010455.html provides a searchable scrollback buffer and the ability to take "snapshots" of text-mode screens.

Recent kernels that have the VGA Console driver can use dramatically more memory for scrollback, provided that the video card can actually handle 64 kb of video memory. Add the line:

#define VGA_CAN_DO_64B

to the start of the file drivers/video/vgacon.c. This feature may become a standard setting in future kernels. If the video frame buffer is also enabled in the kernel, this setting may not affect buffering.

In older kernels, the amount of scrollback is fixed, because it is implemented using the video memory to store the scrollback text. You may be able to get more scrollback in each virtual console by reducing the total number of VC's. See linux/tty.h.

[Chris Karakas]

So it looks like it is possiible to increase this... but it is using video ram.

Scrollback

Scrollback

Same observation here.