xref: /freebsd/usr.bin/gcore/gcore.1 (revision 4b9d6057)
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28.Dd April 24, 2021
29.Dt GCORE 1
30.Os
31.Sh NAME
32.Nm gcore
33.Nd get core images of running process
34.Sh SYNOPSIS
35.Nm
36.Op Fl f
37.Op Fl k
38.Op Fl c Ar core
39.Op Ar executable
40.Ar pid
41.Sh DESCRIPTION
42The
43.Nm
44utility creates a core image of the specified process,
45suitable for use with
46.Xr gdb 1 Pq Pa ports/devel/gdb .
47By default, the core is written to the file
48.Dq Pa core.<pid> .
49The process identifier,
50.Ar pid ,
51must be given on the command line.
52.Pp
53The following options are available:
54.Bl -tag -width indent
55.It Fl c
56Write the core file to the specified file instead of
57.Dq Pa core.<pid> .
58.It Fl f
59Dumps all available segments, excluding only malformed and undumpable
60segments.
61Unlike the default invocation, this flag dumps mappings of devices which
62may invalidate the state of device transactions or trigger other unexpected
63behavior.
64As a result, this flag should only be used when the behavior of the
65application and any devices it has mapped is fully understood and any side
66effects can be controlled or tolerated.
67.It Fl k
68Use the
69.Xr ptrace 2
70.Dv PT_COREDUMP
71kernel facility to write the core dump, instead of reading the process'
72memory and constructing the dump file in
73.Nm
74itself.
75This is faster, and the dump is written by the
76same kernel code that writes core dumps upon fatal signals.
77.El
78.Sh FILES
79.Bl -tag -width /var/log/messages -compact
80.It Pa core.<pid>
81the core image
82.El
83.Sh HISTORY
84A
85.Nm
86utility appeared in
87.Bx 4.2 .
88.Sh BUGS
89Because of the
90.Xr ptrace 2
91usage
92.Nm
93may not work with processes which are actively being investigated with
94.Xr truss 1
95or
96.Xr gdb 1 Pq Pa ports/devel/gdb .
97Additionally, interruptable sleeps may exit with EINTR.
98.Pp
99The
100.Nm
101utility is not compatible with the original
102.Bx 4.2
103version.
104