Check the supported GLIB symbols

You can check the gcc version and other useful information running directly the libc.so library (yes, you can run the library from console): You would see something like this:

user@host-machine:~$ /lib/x86_64-linux-gnu/libc.so.6
GNU C Library (Ubuntu GLIBC 2.27-3ubuntu1) stable release version 2.27.
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Compiled by GNU CC version 7.3.0.
libc ABIs: UNIQUE IFUNC
For bug reporting instructions, please see:
<https://bugs.launchpad.net/ubuntu/+source/glibc/+bugs>.

To check the c++ versions:

$ objdump -x /usr/lib/x86_64-linux-gnu/libstdc++.so.6 | grep GLIBCXX_
$ objdump -x /lib/x86_64-linux-gnu/libc.so.6 | grep GLIBC_

To check the GLIBC versions

& ldd --version

The libc.so file is stored in (ubuntu):

/lib/x86_64-linux-gnu/libc.so.6