Some basic questions

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1

Hi-

Newbie here with some basic questions:

1) I can't get alias to work. I tried alias ll='ls -al', but it doesn't work. When just typing 'alias', the new definition doesn't appear. I'm in a bash shell -- is that the problem. I tried switching to csh, but that didn't seem to help. This brings me to my second question.
2) How can I tell what shell I am in? I thought I was in the bash shell so I typed "csh". The shell prompt remained as $.

Thanks

2

I'm in the BASH shell, and your alias works fine for me. Are you using BASH, or just sh?

Also, are you using these aliases in the shell, or in a script? Aliases are usually turned off in scripts, but you can enable them with 'shopt -s expand_aliases'.

You can tell what shell you're in like this:

$ echo "${SHELL}"
/bin/bash
$
3

'echo $0' will give you your 'current' shell interpreter.

4

no, this doesn't work.

$ echo $0
-bash
$ echo $SHELL
/usr/local/bin/bash
$ csh
>echo $0
csh
>echo $SHELL
/usr/local/bin/bash
>
5

Why does this happen?

6

quoting ''man bash':

       SHELL  The full pathname to the shell is kept in this environment vari-
              able.   If  it is not set when the shell starts, bash assigns to
              it the full pathname of the current user's login shell.

'SHELL' holds the user 'login shell' - which does not change when you change your shell interpreter [bash -> csh]. WHereas '$cho $0' gives you your current shell interpreter in a given shell [regardless of your 'login shell'].