Which variable defines the directories in which a Bash shell searches for executable commands?

`BASHEXEC` is not a standard or recognized environment variable used by the Bash shell to define the search path for executables.

`.bashrc` (or `BASHRC`) is a shell script executed at the start of interactive non-login shells to configure the environment, but it is not the variable itself that defines the command search path.

The `PATH` environment variable is a colon-separated list of directories that the Bash shell systematically searches, in order, to locate and execute commands entered by the user.

`EXECPATH` is not a standard environment variable that Bash uses for locating executable commands.

`PATHRC` is not a standard environment variable in Bash that specifies the directories for command lookup.