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Re: [Crash-utility] less(1) TERM requirements; man page update [was Re: crash CPU bound waiting for user response]
- From: Dave Anderson <anderson redhat com>
- To: "D. Hugh Redelmeier" <hugh mimosa com>, "Discussion list for crash utility usage, maintenance and development" <crash-utility redhat com>
- Subject: Re: [Crash-utility] less(1) TERM requirements; man page update [was Re: crash CPU bound waiting for user response]
- Date: Tue, 10 Jul 2007 10:49:43 -0400
D. Hugh Redelmeier wrote:
| From: Dave Anderson <anderson redhat com>
| Chip Coldwell wrote:
| > On Tue, 3 Jul 2007, D. Hugh Redelmeier wrote:
| > >==> It does not say in what way the terminal is not fully
| > >functional. That seems like a bug.
| > Well, the issue is that the emacs terminal emulator does not fully
| > support the [n]curses escape sequences needed to position the cursor
| > for your pager (e.g. less).
The whole point of termcap/terminfo is to tame the whacky world of
terminal diversity. There is nothing "wrong" with a terminal that
does not have features needed by less(1).
In fact less(1) would almost never be useful within an emacs/jove
terminal window even if it did work: emacs/jove has more appropriate
facilities built in.
The same goes for readline within an emacs/jove terminal.
| I would think the easiest way to deal with this issue would be
| to not allow crash to use "less" if the TERM type is "vanilla".
| And if it is vanilla, fall back to using "more", which is what
| is done now if "less" doesn't exist on the host system.
The name of an entry in termcap/terminfo is not supposed to be
material. One is supposed to make decisions based on the declared
Unfortunately, less(1) does not document what capabilities it
requires: neither in the man page nor in the warning messages. I
don't care enough to read the source code, and in any case anything
learned there would be provisional since it isn't part of the
Getting crash entagled with termcap/terminfo on behalf of less(1) is
probably a bad idea. Mind you, I expect crash already is involved
with termca/terminfo through using readline (I've not checked).
I suspect that the current situation is probably better than trying to
fix it. A simple "set scroll off" cures the problem for a run.
Making this clear in documentation would be a modest improvement.
Fine, but at a minimum I propose the addition of a "--more" command
line argument to force its use instead of "less". With that in place,
I've verified that crash scrolling works fine using the "vanilla"
TERM type, and I presume that using "more" for scrolling would suffice
within the emacs/jove/vanilla environment as well?
Is there a simple way of turning off readline? To make the problem
harder: I want to do it some times (i.e. when running crash under jove)
but not at others (i.e. when running crash directly in an xterm).
Here is a proposed patch to the man page.
RCS file: RCS/crash.8,v
retrieving revision 1.1
diff -u -r1.1 crash.8
--- crash.8 2007/07/09 15:41:55 1.1
+++ crash.8 2007/07/09 18:16:56
@@ -5,7 +5,7 @@
.TH CRASH 8
crash \- Analyze Linux crash data or a live system
@@ -44,7 +44,7 @@
core dump has been created by the Red Hat
facility. It is loosely based on the SVR4 UNIX crash
-command, but has been signficantly enhanced
+command, but has been significantly enhanced
by completely merging it with the
debugger. The marriage of the two effectively combines the
@@ -207,11 +207,11 @@
disassembles memory, either entire kernel functions, from a
location for a specified number of instructions, or from the start of a
-fuction up to a specified memory location.
+function up to a specified memory location.
evalues an expression or numeric type and displays the result
-in hexidecimal, decimal, octal and binary.
+in hexadecimal, decimal, octal and binary.
@@ -230,7 +230,7 @@
in the system.
-displays the tasks using the specifed file or socket.
+displays the tasks using the specified file or socket.
passes its argument to the underlying
@@ -274,7 +274,7 @@
display various network related data.
-passes its argumnts to the
+passes its arguments to the
"print" command for evaluation and display.
@@ -361,11 +361,54 @@
modifies the contents of memory. When writing to memory on
a live system, this command should obviously be used with great care.
+Command input is read using
+is set to
+then suitable keybindings are used. This can be overridden by ``\fBset\ vi\fP''
+or ``\fBset\ emacs\fP'' commands, but only in
+.IR ~/.crashrc .
+does not work, look for a newer version: kernel evolution frequently makes
+The command ``\fBset\ scroll\ off\fP'' will cause output to be sent directly to
+the terminal rather than through a paging program. This is useful,
+for example, if you are running
+in a window of
+.BR emacs .
Dave Anderson <anderson redhat com> wrote
Jay Fenlason <fenlason redhat com> wrote this man page.
.SH "SEE ALSO"
+provides more complete and accurate documentation than this manpage.
+The home page of
+.IR crash .
+.BR netdump (8),
+.BR gdb (1)
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