Candidate for most silly question, but here it goes:

[doug]

On Tue, 4 May 2021, Harry Schmalzbauer wrote:

> Hi!
>
> #> file /usr/lib/libc.so
> /usr/lib/libc.so: ASCII text
>
>
> #> cat /usr/lib/libc.so
> /* $FreeBSD$ */
> GROUP ( /lib/libc.so.7 /usr/lib/libc_nonshared.a )
>
>
> Does this make sense in any way?
>
> Accidentally stumbled across while trying out thunderbird, which claims:
> JavaScript error: resource:///modules/CLib.jsm, line 46: Error: couldn't open 
> library libc.so: /usr/lib/libc.so: invalid file format
>
>
> Thanks for hints (I have some brief knwoledge about dynamically linked 
> binaries, but I'm not aware of linker hints - which is what I see to my 
> understanding).
>
> -harry

I'm pretty sure you arn't the only. At least I'm in the running with you. 
That said on my 12.2-RELEASE-p4 system I get:

cat /usr/lib/libc.so
/* $FreeBSD: releng/12.2/lib/libc/libc.ldscript 258283 2013-11-17 22:52:17Z peter $ */
GROUP ( /lib/libc.so.7 /usr/lib/libc_nonshared.a 
/usr/lib/libssp_nonshared.a )

My guess is that is a way of telling various flavors of firefox which 
dynamic lib to use. In any case that's whats there