Trouble understanding parameter substitution in a script

Question

I\'m trying to understand a bash script whose first four lines are:

#!/bin/sh
SCRIPT=\"`basename $0 | sed \'s/\\..*$//\'`\"
CONFIG=${1:-$HOME/.$SCRIPT}
DIR=${2:-         


        

Answer 1

From man bash:

   ${parameter:-word}
          Use Default Values.  If parameter is unset or null, the expansion of word is substituted.  Other‐
          wise, the value of parameter is substituted.

Very easy to find, with man bash, and then /:-. The slash introduces a search, and :- is just the content to search for. Else, searching in bash can get very boring, because it is huge, but here it is the first hit.