Is it possible to get a core dump of a running process and its symbol table?

StackOverflow https://stackoverflow.com/questions/68160

  •  09-06-2019
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Question

Is it possible to get gdb or use some other tools to create a core dump of a running process and it's symbol table? It would be great if there's a way to do this without terminating the process.

If this is possible, what commands would you use? (I'm trying to do this on a Linux box)

Was it helpful?

Solution 

$ gdb --pid=26426
(gdb) gcore
Saved corefile core.26426
(gdb) detach

OTHER TIPS

Or run gcore $(pidof processname).

This has the benefit (over running gdb and issuing commands to the CLI) that you attach and detach in the shortest possible time.

Note: The following method will terminate the running process & requires the symbols too.

You can send one of the following signals (with action=core) to the running process:
From: http://man7.org/linux/man-pages/man7/signal.7.html

       Signal     Value     Action   Comment
       ──────────────────────────────────────────────────────────────────────
       SIGHUP        1       Term    Hangup detected on controlling terminal
                                     or death of controlling process
       SIGINT        2       Term    Interrupt from keyboard
       SIGQUIT       3       Core    Quit from keyboard
       SIGILL        4       Core    Illegal Instruction
       SIGABRT       6       Core    Abort signal from abort(3)
       SIGFPE        8       Core    Floating point exception
       SIGKILL       9       Term    Kill signal
       SIGSEGV      11       Core    Invalid memory reference
       SIGPIPE      13       Term    Broken pipe: write to pipe with no
                                     readers
       SIGALRM      14       Term    Timer signal from alarm(2)
       SIGTERM      15       Term    Termination signal
       SIGUSR1   30,10,16    Term    User-defined signal 1
       SIGUSR2   31,12,17    Term    User-defined signal 2
       SIGCHLD   20,17,18    Ign     Child stopped or terminated
       SIGCONT   19,18,25    Cont    Continue if stopped
       SIGSTOP   17,19,23    Stop    Stop process
       SIGTSTP   18,20,24    Stop    Stop typed at terminal
       SIGTTIN   21,21,26    Stop    Terminal input for background process
       SIGTTOU   22,22,27    Stop    Terminal output for background process

Like so:
kill <signal> <pid>

And once you have the core, you can open in gdb along with the symbol file.

You can used generate-core-file command in gdb to generate core dump of running process.

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