Not every ipcalc(1) supports '-r' about asn HOT 3 CLOSED

Well, -r (deaggregate) was introduced in ipcalc v0.36-pre1 which dates back to more than 17 years ago - I guess we shall have to compromise on that.
Which version are you using, and on what OS?

from asn.

I didn't dig into these details, the system is a fully up-to-date Red Hat Enterprise Linux 7 or CentOS 7 being initially released in 2014 and receiving support until 2024. Not sure which ipcalc flavor you linked, but mine is a ELF binary, not a Perl script. The source code in the SRPM is very similar to this ipcalc.c.

But yes, declaring RHEL/CentOS 7 as too old to ship a usable ipcalc might be a valid option, too.

from asn.

Ah, that might be it then. Every other supported distro I initially tested the script on, shipped the original ipcalc (which is a perl script). Back then, I remember ruling out some older distro versions because of such shortcomings (that is why I initially specified CentOS 8 and not just CentOS).

from asn.