.\"	$NetBSD: crash.8,v 1.8 2019/03/23 02:07:32 mrg Exp $
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.Dd March 22, 2019
.Dt CRASH 8
.Os
.Sh NAME
.Nm crash
.Nd examine and debug system images
.Sh SYNOPSIS
.Nm
.Op Fl w
.Op Fl M Ar core
.Op Fl N Ar kernel
.Sh DESCRIPTION
The
.Nm
command is used to examine and debug system images.
.Pp
If run without any arguments,
.Nm
operates on the running system.
.Pp
The options are as follows:
.Bl -tag -width xpalidocious
.It Fl M Ar core
Operate on the specified crash dump instead of the default
.Pa /dev/mem .
Crash dumps should be from the same version of the system and same machine
architecture as the running version of
.Nm crash ,
and must be uncompressed.
.It Fl N Ar kernel
Extract the name list from the specified kernel instead of the default
.Pa /dev/ksyms .
.It Fl w
Enable writing.
.El
.Pp
The command syntax used by
.Nm
is the same as the in-kernel debugger.
See the
.Xr ddb 4
manual page for more information.
.Pp
Operations and facilities that require a running system, such as breakpoints,
are not supported by
.Nm crash .
.Pp
.Nm
does not provide pagination.
However, by using the pipe symbol, output may be sent to commands available
from the shell.
For example:
.Bd -literal -offset abcd
crash> ps | more
crash> ps | grep ioflush
.Ed
.Sh EXAMPLES
You can obtain a full list of all kernel stack traces with a shell pipeline
like the following:
.Bd -literal -offset abcd
# echo ps | crash | grep '^[0-9]' | cut -c 30-46 | \\
  sed 's,^,bt/a ,' | crash
.Ed
.Sh SEE ALSO
.Xr ps 1 ,
.Xr vmstat 1 ,
.Xr ddb 4 ,
.Xr pstat 8
.Sh HISTORY
The
.Nm
command appeared in
.Nx 6.0 .
.Sh BUGS
The
.Nm
command for the sparc port is unstable.