Prompt “-bash-3.2$” vs. “bash-3.2$” in SunOS 5.10

Question

When I log into a server running SunOS 5.10, my prompt initially is "-bash-3.2$"

Then when I run the following commands, I can see that the prompt is slightly different after typing bash (it no longer begins with a dash), yet echo $SHELL gives the same result.

-bash-3.2$ echo $SHELL
/bin/bash
-bash-3.2$ bash
bash-3.2$ echo $SHELL
/bin/bash

What does this mean, and what implications does it have?

Answer 1

PS1 default value under bash is \s-\v\$

• \s is replaced by the name of your shell ($0)
• \v is the bash version

The leading - is just due to the first shell being a login shell. This dash is used to differentiate login shells from other ones. The second shell is not a login shell so hasn't that prefix.

PS1 stays like this in your case because none of the scripts sourced at startup override it.

There is no implication about these prompts.

By the way, this OS is more commonly referred to as "Solaris 10" than "SunOS 5.10".

Answer 2

The bash manual explains it in the Invoking Bash section:

A login shell is one whose first character of argument zero is ‘-’, or one invoked with the --login option.

Login shells invoke different startup files.