See section Bash Startup Files . The version number of the current instance of Bash. A readonly array variable whose members hold version information for this instance of Bash. The patch level. The build version.
Directories appear in the stack in the order they are displayed by the dirs builtin.
Assigning to members of this array variable may be used to modify directories already in the stack, but the pushd and popd builtins must be used to add and remove directories. Assignment to this variable will not change the current directory. This variable is readonly. A colon-separated list of suffixes to ignore when performing filename completion. The history comment character causes history substitution to be skipped for the remaining words on the line.