What are difference between -bash and bash?

Question

When I log in as root and enter some random non-existing command, it says:

root@localhost:~# asdf
-bash: asdf: command not found
root@localhost:~# 

But when I do the same thing as user rakinar2 it says:

rakinar2@localhost:~$ asdf
bash: asdf: command not found
rakinar2@localhost:~$ 

Now what are difference between -bash and bash?

Answer 1

Bash started with a dash - as the first character for the command name (argument #0) starts as a login shell. (So does a shell given the -l / --login switch.) That affects the startup files it reads.

See: 6.1 Invoking Bash and 6.2 Bash Startup Files in the manual.