Hello,

The patch below changes occurrences of ‘/usr/bin/file’ to just ‘file’.

The impetus is that on systems using GNU Guix, NixOS, GoboLinux, and
others, the ‘file’ command is not available as /usr/bin/file, so it must
instead be taken from $PATH.

(I conservatively left ‘/usr/bin/file’ for more centralized systems such
as BSD, IRIX, etc. where it’s more likely to be a valid command.)

WDYT?

Ludo’.