I need to use my $PATH in Emacs to run some commands. How can I make Emacs use it? I installed Emacs from Ubuntu repositories.
A more general solution (to set all variables and aliases, not just PATH) is given in https://stackoverflow.com/a/12229404/1190077 -- the key is to set:
(setq shell-command-switch "-ic")
which overrides the default "-c" (execute the following command). The addition of "-i" forces the bash shell into interactive mode, which leads to the sourcing of ~/.bashrc.