DDB(8)                  FreeBSD System Manager's Manual                 DDB(8)

NAME
     ddb - configure DDB kernel debugger properties

SYNOPSIS
     ddb capture [-M -core] [-N -system] print
     ddb capture [-M -core] [-N -system] status
     ddb script scriptname
     ddb script scriptname=script
     ddb scripts
     ddb unscript scriptname
     ddb pathname

DESCRIPTION
     The ddb utility configures certain aspects of the ddb(4) kernel debugger
     from user space that are not configured at compile-time or easily via
     sysctl(8) MIB entries.

     To ease configuration, commands can be put in a file which is processed
     using ddb as shown in the last synopsis line.  An absolute pathname must
     be used.  The file will be read line by line and applied as arguments to
     the ddb utility.  Whitespace at the beginning of lines will be ignored as
     will lines where the first non-whitespace character is `#'.

OUTPUT CAPTURE
     The ddb utility can be used to extract the contents of the ddb(4) output
     capture buffer of the current live kernel, or from the crash dump of a
     kernel on disk.  The following debugger commands are available from the
     command line:

     capture [-M core] [-N system] print
             Print the current contents of the ddb(4) output capture buffer.

     capture [-M core] [-N system] status
             Print the current status of the ddb(4) output capture buffer.

SCRIPTING
     The ddb utility can be used to configure aspects of ddb(4) scripting from
     user space; scripting support is described in more detail in ddb(4).
     Each of the debugger commands is available from the command line:

     script scriptname
             Print the script named scriptname.

     script scriptname=script
             Define a script named scriptname.  As many scripts contain
             characters interpreted in special ways by the shell, it is
             advisable to enclose script in quotes.

     scripts
             List currently defined scripts.

     unscript scriptname
             Delete the script named scriptname.

EXIT STATUS
     The ddb utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     The following example defines a script that will execute when the kernel
     debugger is entered as a result of a break signal:

           ddb script kdb.enter.break="show pcpu; bt"

     The following example will delete the script:

           ddb unscript kdb.enter.break

     For further examples, see the ddb(4) and textdump(4) manual pages.

SEE ALSO
     ddb(4), textdump(4), sysctl(8)

HISTORY
     The ddb utility first appeared in FreeBSD 7.1.

AUTHORS
     Robert N M Watson

BUGS
     Ideally, ddb would not exist, as all pertinent aspects of ddb(4) could be
     configured directly via sysctl(8).

FreeBSD 13.1-RELEASE-p6        December 24, 2008       FreeBSD 13.1-RELEASE-p6