There are some fancy build-in variables in bash that I picked up from others’ scripts. They start with a dollar sign. Guess I’ll take some notes. (mostly stole from SO)[https://stackoverflow.com/questions/5163144/what-are-the-special-dollar-sign-shell-variables]

  • $# number of arguments

  • $@ and $* return all the parameters, but answer on SO

$@ behaves like $* except that when quoted the arguments are broken up properly if there are spaces in them.

  • $? was last command successful?

  • $0 $1 $2 ... positional arguments, $0 gives the

  • $# number of positional parameters ($0 excluded)

  • $- current options set for the shell

  • $$ pid of the current shell

  • $_ most recent parameter (probably rarely used)

  • $IFS field separator