Difference between normal shell and login shell

Manish · 02-24-2002, 05:10 AM

What is the difference between running a shell (e.g. bash) as a normal shell VS as a login shell (with the option -login, or prefixing hyphen to its sym. link) ??

Thanks.

trickykid · 03-09-2002, 02:17 PM

I don't understand your question. I thought a shell was a shell, either using bash, sh, csh, tcsh... etc etc... logging in or already logged in..

-trickykid

jeremy · 03-09-2002, 03:25 PM

You can invoke bash as a login shell or as an interactive shell. From the man page:

Quote:

A login shell is one whose first character of argument zero is a -, or one started with the -login flag.

An interactive shell is one whose standard input and output are both connected to terminals (as determined by
isatty(3)), or one started with the -i option. PS1 is set and $- includes i if bash is interactive, allowing a
shell script or a startup file to test this state.

Login shells:
On login (subject to the -noprofile option):
if /etc/profile exists, source it.

if ~/.bash_profile exists, source it,
else if ~/.bash_login exists, source it,
else if ~/.profile exists, source it.

On exit:
if ~/.bash_logout exists, source it.

Non-login interactive shells:
On startup (subject to the -norc and -rcfile options):
if ~/.bashrc exists, source it.

Non-interactive shells:
On startup:
if the environment variable ENV is non-null, expand
it and source the file it names, as if the command
if [ "$ENV" ]; then . $ENV; fi
had been executed, but do not use PATH to search
for the pathname. When not started in Posix mode, bash
looks for BASH_ENV before ENV.

If Bash is invoked as sh, it tries to mimic the behavior of sh as closely as possible. For a login shell, it
attempts to source only /etc/profile and ~/.profile, in that order. The -noprofile option may still be used to
disable this behavior. A shell invoked as sh does not attempt to source any other startup files.

--jeremy

Manish · 03-09-2002, 10:02 PM

Thanks jeremy.