coredumpctl(1) — Chainguard OS Manuals

COREDUMPCTL(1)

coredumpctl

COREDUMPCTL(1)

.SH "NAME" coredumpctl - Retrieve and process saved core dumps and metadata

.SH "SYNOPSIS"

.HP 288u

coredumpctl
[OPTIONS...]
{COMMAND}
[PID|COMM|EXE|MATCH...]

.SH "DESCRIPTION"

.PP coredumpctl is a tool that can be used to retrieve and process core dumps and metadata which were saved by systemd-coredump(8).

.SH "COMMANDS"

.PP The following commands are understood:

.PP list

List core dumps captured in the journal matching specified characteristics. If no command is specified, this is the implied default.

The output is designed to be human-readable and contains a table with the following columns:

.PP TIME

The timestamp of the crash, as reported by the kernel.

Added in version 233.

.RE

.PP PID

The identifier of the process that crashed.

Added in version 233.

.RE

.PP UID, GID

The user and group identifiers of the process that crashed.

Added in version 233.

.RE

.PP SIGNAL

The signal that caused the process to crash, when applicable.

Added in version 233.

.RE

.PP COREFILE

Information whether the coredump was stored, and whether it is still accessible: none means the core was not stored, - means that it was not available (for example because the process was not terminated by a signal), present means that the core file is accessible by the current user, journal means that the core was stored in the journal, truncated is the same as one of the previous two, but the core was too large and was not stored in its entirety, error means that the core file cannot be accessed, most likely because of insufficient permissions, and missing means that the core was stored in a file, but this file has since been removed.

Added in version 233.

.RE

.PP EXE

The full path to the executable. For backtraces of scripts this is the name of the interpreter.

Added in version 233.

.RE
.sp

It's worth noting that different restrictions apply to data saved in the journal and core dump files saved in /var/lib/systemd/coredump, see overview in systemd-coredump(8). Thus it may very well happen that a particular core dump is still listed in the journal while its corresponding core dump file has already been removed.

Added in version 215.

.RE

.PP info

Show detailed information about the last core dump or core dumps matching specified characteristics captured in the journal.

Added in version 215.

.RE

.PP dump

Extract the last core dump matching specified characteristics. The core dump will be written on standard output, unless an output file is specified with --output=.

Added in version 215.

.RE

.PP debug

Invoke a debugger on the last core dump matching specified characteristics. By default, gdb(1) will be used. This may be changed using the --debugger= option or the $SYSTEMD_DEBUGGER environment variable. Use the --debugger-arguments= option to pass extra command line arguments to the debugger.

Added in version 239.

.RE

.SH "OPTIONS"

.PP The following options are understood:

.PP -h, --help

Print a short help text and exit.

.RE
.PP --version

Print a short version string and exit.

.RE
.PP --no-pager

Do not pipe output into a pager.

.RE
.PP --no-legend

Do not print the legend, i.e. column headers and the footer with hints.

.RE
.PP --json=MODE

Shows output formatted as JSON. Expects one of short (for the shortest possible output without any redundant whitespace or line breaks), pretty (for a pretty version of the same, with indentation and line breaks) or off (to turn off JSON output, the default).

.RE

.PP -1

Show information of the most recent core dump only, instead of listing all known core dumps. Equivalent to --reverse -n 1.

Added in version 215.

.RE

.PP -n INT

Show at most the specified number of entries. The specified parameter must be an integer greater or equal to 1.

Added in version 248.

.RE

.PP -S, --since

Only print entries which are since the specified date.

Added in version 233.

.RE

.PP -U, --until

Only print entries which are until the specified date.

Added in version 233.

.RE

.PP -r, --reverse

Reverse output so that the newest entries are displayed first.

Added in version 233.

.RE

.PP -F FIELD, --field=FIELD

Print all possible data values the specified field takes in matching core dump entries of the journal.

Added in version 215.

.RE

.PP -o FILE, --output=FILE

Write the core to FILE.

Added in version 215.

.RE

.PP --debugger=DEBUGGER

Use the given debugger for the debug command. If not given and $SYSTEMD_DEBUGGER is unset, then gdb(1) will be used.

Added in version 239.

.RE

.PP -A ARGS, --debugger-arguments=ARGS

Pass the given ARGS as extra command line arguments to the debugger. Quote as appropriate when ARGS contain whitespace. (See Examples.)

Added in version 248.

.RE

.PP --file=GLOB

Takes a file glob as an argument. If specified, coredumpctl will operate on the specified journal files matching GLOB instead of the default runtime and system journal paths. May be specified multiple times, in which case files will be suitably interleaved.

Added in version 246.

.RE

.PP -D DIR, --directory=DIR

Use the journal files in the specified DIR.

Added in version 225.

.RE

.PP --root=ROOT

Use root directory ROOT when searching for coredumps.

Added in version 252.

.RE

.PP --image=image

Takes a path to a disk image file or block device node. If specified, all operations are applied to file system in the indicated disk image. This option is similar to --root=, but operates on file systems stored in disk images or block devices. The disk image should either contain just a file system or a set of file systems within a GPT partition table, following the UAPI.2 Discoverable Partitions Specification[1]. For further information on supported disk images, see systemd-nspawn(1)'s switch of the same name.

Added in version 252.

.RE

.PP --image-policy=policy

Takes an image policy string as argument, as per systemd.image-policy(7). The policy is enforced when operating on the disk image specified via --image=, see above. If not specified, defaults to the * policy, i.e. all recognized file systems in the image are used.

.RE

.PP -q, --quiet

Suppresses informational messages about lack of access to journal files and possible in-flight coredumps.

Added in version 233.

.RE

.PP --all

Look at all available journal files in /var/log/journal/ (excluding journal namespaces) instead of only local ones.

Added in version 250.

.RE

.SH "MATCHING"

.PP A match can be:

.PP PID

Process ID of the process that dumped core. An integer.

Added in version 215.

.RE

.PP COMM

Name of the executable (matches COREDUMP_COMM=). Must not contain slashes.

Added in version 215.

.RE

.PP EXE

Path to the executable (matches COREDUMP_EXE=). Must contain at least one slash.

Added in version 215.

.RE

.PP MATCH

General journalctl match filter, must contain an equals sign (=). See journalctl(1).

Added in version 215.

.RE

.SH "EXIT STATUS"

.PP On success, 0 is returned; otherwise, a non-zero failure code is returned. Not finding any matching core dumps is treated as failure.

.SH "ENVIRONMENT"

.PP $SYSTEMD_DEBUGGER

Use the given debugger for the debug command. See the --debugger= option.

Added in version 239.

.RE

.SH "EXAMPLES"

.PP Example 1. List all the core dumps of a program

$ coredumpctl list /usr/lib64/firefox/firefox
TIME       PID  UID  GID SIG     COREFILE EXE                         SIZE
Tue ...   8018 1000 1000 SIGSEGV missing  /usr/lib64/firefox/firefox     -
Wed ... 251609 1000 1000 SIGTRAP missing  /usr/lib64/firefox/firefox     -
Fri ... 552351 1000 1000 SIGSEGV present  /usr/lib64/firefox/firefox 28.7M

.PP The journal has three entries pertaining to /usr/lib64/firefox/firefox, and only the last entry still has an available core file (in external storage on disk).

.PP Note that coredumpctl needs access to the journal files to retrieve the relevant entries from the journal. Thus, an unprivileged user will normally only see information about crashing programs of this user.

.PP Example 2. Invoke gdb on the last core dump

$ coredumpctl debug

.PP Example 3. Use gdb to display full register info from the last core dump

$ coredumpctl debug --debugger-arguments="-batch -ex 'info all-registers'"

.PP Example 4. Show information about a core dump matched by PID

$ coredumpctl info 6654


           PID: 6654 (bash)


           UID: 1000 (user)


           GID: 1000 (user)


        Signal: 11 (SEGV)


     Timestamp: Mon 2021-01-01 00:00:01 CET (20s ago)


  Command Line: bash -c $'kill -SEGV $$'


    Executable: /usr/bin/bash


 Control Group: /user.slice/user-1000.slice/...


          Unit: user@1000.service


     User Unit: vte-spawn-....scope


         Slice: user-1000.slice


     Owner UID: 1000 (user)


       Boot ID: ...


    Machine ID: ...


      Hostname: ...


       Storage: /var/lib/systemd/coredump/core.bash.1000.....zst (present)


  Size on Disk: 51.7K


       Message: Process 130414 (bash) of user 1000 dumped core.


                Stack trace of thread 130414:


                #0  0x00007f398142358b kill (libc.so.6 + 0x3d58b)


                #1  0x0000558c2c7fda09 kill_builtin (bash + 0xb1a09)


                #2  0x0000558c2c79dc59 execute_builtin.lto_priv.0 (bash + 0x51c59)


                #3  0x0000558c2c79709c execute_simple_command (bash + 0x4b09c)


                #4  0x0000558c2c798408 execute_command_internal (bash + 0x4c408)


                #5  0x0000558c2c7f6bdc parse_and_execute (bash + 0xaabdc)


                #6  0x0000558c2c85415c run_one_command.isra.0 (bash + 0x10815c)


                #7  0x0000558c2c77d040 main (bash + 0x31040)


                #8  0x00007f398140db75 __libc_start_main (libc.so.6 + 0x27b75)


                #9  0x0000558c2c77dd1e _start (bash + 0x31d1e)

.PP Example 5. Extract the last core dump of /usr/bin/bar to a file named bar.coredump

$ coredumpctl -o bar.coredump dump /usr/bin/bar

NOTES

1.: UAPI.2 Discoverable Partitions Specification

https://uapi-group.org/specifications/specs/discoverable_partitions_specification

systemd 262.2