That’s very strange!
The awk (gawk) on my 16.04 supports the “hew style” (available when I first used GNU tools in the 1990s) --long-switches.
Can you tell what package provided your awk? Did you install some “minimal” Ubuntu distribution?
What does
dpkg -l |grep awk
say?
I’m working on a PR for this, but found another error that I’d like to resolve before sumitting. The awk (gawk) that is typically installed on Ubuntu supports the --field-separator switch. It looks like there is an original-awk package that installs an awk that must be the one that doesn’t support GNU-style switches. @Shivam_Trivedi or @Fajfi can you see what version of awk you have installed?