Oneliner to diff a set of files pairwise in different tabs with Vim:
gvim -R -c 'for i in range(1, argc() - 1) | if i % 2 == 1 | rightbelow vertical diffsplit | next | diffthis | else | tabedit | next | endif | endfor' a b c d
Oneliner to diff a set of files pairwise in different tabs with Vim:
gvim -R -c 'for i in range(1, argc() - 1) | if i % 2 == 1 | rightbelow vertical diffsplit | next | diffthis | else | tabedit | next | endif | endfor' a b c d