$ perl -nE "/: / and $c += (split/: /)[0]; if( eof(ARGV) ){ say qq[SUM.$ARGV =$c]; $c=0 }" tmp_*
syntax error at -e line 1, near "+="
syntax error at -e line 1, near "; ="
Execution of -e aborted due to compilation errors.

##</code><code>##

$ c=10
$ echo c
c
$ echo $c
10
$ echo "The total is: $c"
The total is: 10
$ echo 'The total is: $c'
The total is: $c