Somewhat disappointingly, tr doesn’t support \s otherwise we could have had

tr -d ’\s’

to give

gcc unpack_pi.c && ./a.out 1 100000000 < pi100m.hexbin.000 | tr -d ’\s’ > pi100mformat.txt

Instead we have to use

tr -d ’[:space:]’

which is only one character less that the original perl

We could restrict ourselves to spaces, tabs and new lines to lose four characters over the perl.

tr -d ’ \n\t’

I blame the silly long file names anyway...—Roger