core dumped message is not captured in STDERR

Question

I used to call my program with this line in bash shell to capture all stdout and stderr messages in the log file

./a.out input.txt 2>&1 | tee log

The log file shows no error but by examining the log, it's obvious that there's a problem and program terminates abruptly in the middle of execution.

I have also tried these but the result is the same:

./a.out input.txt > log 2>&1

./a.out input.txt |& tee log

When I run it without any redirection like this:

./a.out input.txt

I see the error message in my terminal window at the end:

*** Error in `./a.out': free(): invalid pointer: 0x000000000169b268 ***
Aborted (core dumped)

So, why I cannot capture the "core dumped" message in my log? What should I do to do so?

Answer 1

There are 2 error messages here:

*** Error in `./a.out': free(): invalid pointer: 0x000000000169b268 ***

This comes from glibc, and is printed on the current tty, if it exists.

If you want it printed to stderr (wherever stderr is redirected), you must set the LIBC_FATAL_STDERR_ prior to starting the program. e.g. in bash do:

export LIBC_FATAL_STDERR_=1

The other message

Aborted (core dumped)

This comes from the shell that started your program, by the shell examining the status of wait(). If the program isn't run by a shell, or e.g. is run by a shell that have terminated, you'll not be able to capture that message. Even if the shell havn't terminated, the stderr of that shell isn't redirected to your log file.

You might get around that by doing:

 { ./a.out input.txt ; } >log 2>&1

See also redirection of ./a.out is not capturing segmentation fault)