dumper

Dump the postmortem state of a program (QNX)

Syntax:

dumper [-bFfmnPStvw] [-D path] [-d path] [-N max_files]
       [-p pid] [-s size[G|M|K]]
       [-U user_name | uid[:gid[,sup_gid]*]]]
       [-z level] &

Options:

-b

Attempt to slog a backtrace (libbacktrace.so.1 must be available).

-D path

The same as -d, but without querying authman.

-d path

The directory in which to place dumps, if authman doesn't supply an application sandbox path. The default is the home directory of user that started the process, or /tmp if none.

-F

Run at a fixed priority.

-f

Follow soft links for the creation of the dump files. The use of this option has security implications.

-m

Don't dump memory.

-N max_files

Save sequential dumps, to a maximum of the given number of files. Each dump is saved in a file whose name is in the form:

executable.num.core

where num starts at 1 and increases until the filename doesn't already exist.

-n

Save sequential dumps. Each dump is saved in a file whose name is in the form:

executable.num.core

where num starts at 1 and increases until the filename doesn't already exist.

-S

Disable the dumping of shared memory mappings.

-P

Dump the physical memory mappings.

-p pid

Save a dump file for this process immediately, and then exit dumper.

-s size[G|M|K]

Set the maximum core size, in bytes.

-t

Dump the stack of the errant thread only, instead of for all threads.

-U user_name

-U uid[:gid[,sup_gid]*]]

Once running, run as the specified user, so that the program doesn't need to run as root:

In the first form, the service sets itself to be the named user and uses that user's groups. This form depends on the /etc/passwd and /etc/group files.
In the second form, the service sets its user ID, and optionally its group ID and supplementary groups, to the values provided.

-v

Be verbose.

-w

Make core files world-readable.

-z level

Use gzip to compress the core files. The compression level must be in the range from 1 (fastest) through 9 (best compressed).

Description:

The dumper utility runs in the background and provides a postmortem dump service for all processes. Whenever a program terminates abnormally, a dump of the current state of the program is written to disk. The dump filename is the same as the program name with a .core extension. For example, if the program name is experiment, the dump is written to experiment.core in your home directory.

Core dumps are placed in the logs directory in the application's sandbox.
Dump files can be large, so make sure the destination filesystem has lots of space.

The -p option lets you get a dump immediately for a particular process. If you specify -p, dumper doesn't run in the background, but exits right away.

You can use a debugger such as gdb to examine a dump file:

gdb program_binary program_core

A program may terminate in one of two ways: it may exit cleanly under its own control, returning an exit status, or it may be forcibly terminated by the receipt of a signal that it isn't prepared to handle. In the latter case, dumper writes a dump file for the following set of signals:

Signal	Description
SIGABRT	Program-called abort function
SIGBUS	Parity error
SIGEMT	EMT instruction (emulation trap) Note that SIGEMT and SIGDEADLK use the same signal number.
SIGFPE	Floating-point error or division by zero
SIGILL	Illegal instruction executed
SIGQUIT	Quit
SIGSEGV	Segmentation violation
SIGSYS	Bad argument to a system call
SIGTRAP	Trace trap (not reset when caught)
SIGXCPU	Exceeded the CPU limit
SIGXFSZ	Exceeded the file size limit

You can force the dump of a running program by setting one of the preceding signals, assuming that the program isn't masking or handling the signal itself.

To force a dump using the slay utility and the process name:

slay -s SIGABRT process_name

Examples:

Start dumper, with dump files to be written to the default directory:

dumper &

Start dumper, with dump files to be placed in the directory /home/dumps:

dumper -d /home/dumps &

Files:

/proc/dumper: A special entry in the /proc filesystem (see procnto*) that receives notification when a process terminates abnormally.

Exit status:

The dumper utility normally doesn't terminate. However, it may terminate if it encounters an error on startup (for instance, if it wasn't run by root) or if it receives a signal.

0: A signal was received and dumper shut down successfully.
1: An error was encountered on startup (not run by root or bad command-line options).