A typical image build will update the dashboard 3500-4500 times. This change
avoids two process forks (cat, wc) per update, and the remaining $(< file) is
faster than $(cat file).
See: https://www.gnu.org/software/bash/manual/html_node/Command-Substitution.html
"
...
Bash performs the expansion by executing command in a subshell environment and replacing
the command substitution with the standard output of the command, with any trailing newlines
deleted. Embedded newlines are not deleted, but they may be removed during word splitting. The
command substitution $(cat file) can be replaced by the equivalent but faster $(< file).
"
Testing indicates var=$(< file) is twice as fast as var=$(cat file).
