What do the characters in the bash environment variable $- mean?

Question

I\'ve been looking through some of the .bashrc and .profile scripts that come with various Linux distros and am seeing that sometimes they check $-.

Her

Answer 1

From man bash:

-

Expands to the current option flags as specified upon invocation, by the set builtin command, or those set by the shell itself (such as the -i option).

So these are the current options that control the behavior of the shell. In particular:

• h: Cache location of binaries in the $PATH. Speeds up execution, but fails if you move binaries around during the shell session.
• i: The current shell is interactive
• m: Job control is enabled
• B: Brace expansion is enabled
• H: History substitution like !-1