Just curious: BASH variable $-

stormcloud · 05-06-2009, 04:08 AM

Hi,

I'm curious; I know that bash supports a variable called $- which gives you information about how the shell it's self is configured, but i don't know much more then that.

Can anybody point me to a good web site that explains what each of the characters in the returned string means. Google, altavista, yahoo etc get a bit confused when I search on $-

Thanks.

druuna · 05-06-2009, 04:26 AM

Hi,

Take a look at bash's manpage, especially the set [--abefhkmnptuvxBCHP] section.

The i isn't mentioned (if it shows up at all after echo $-), this tells you if bash is interactive (i is shown) or not.

Hope this helps.

colucix · 05-06-2009, 04:32 AM

Just look at man set and man bash. They describes all the available options. On my system running CentOS 5.3 I have:

Code:

$ echo $-
himBH

where

Code:

-h      Remember  the  location  of  commands  as  they  are looked up for execution.  This is
        enabled by default.
-i      If the -i option is present, the shell is interactive.
-m      Monitor  mode.   Job control is enabled.
-B      The  shell  performs  brace  expansion.
-H      Enable !  style history substitution.

amysaraantony · 05-06-2009, 11:44 AM

The MAN command is your friend sir!

Debian

stormcloud · 05-07-2009, 02:37 AM

Thanks for the advice everybody. Much appreciated.

I never thought of looking at man for bash it's self, and you can't run "man $-"