UNIX for Dummies Questions & Answers

1)
ssh a@b
echo $USER it display the correct value as a (even though i have not defined it in .profile)

2)
remsh b -l a
echo $USER it does not display the value as a (variable is not set

any idea why $USER variable is not initialized when i login via remsh or rlogin but shows the correct value via ssh login

i guess there are some system profile /shell variables which generate these values and it is not getting initialized by remsh/rlogin

can someone pls suggest a solution for this ?

thanks

Often variables such as $USER are set in the global profile. ssh runs these global profiles when the user logs on. remsh, however, doesnt. Most shells, however will allow you to run then as a login shell, so for instance if you were running "/usr/bin/env" try running something like:

Code:

remsh b -l a "/bin/sh -l -c /usr/bin/env"

(paths and arguments to your shell can vary on different O/S so I would check your man pages)

seems /usr/bin/env is already getting initialized by remsh
i checked the variable defined in this is getting initialized

echo $LOGNAME

still i am not able to see the value of $USER perhaps its coming from some other file

I presume from the use of "remsh", that this is a HP-UX machine ? If it is, what version is it ? I believe HP-UX 11.11 and below had a remshd that didnt use the normal methods of creating a user session (namely by calling PAM - Pluggable Authentication Modules).

Perhaps instead of using remsh you could use ssh with a command (you can set ssh up to not ask for passwords if needed) - this would also be much more secure...remsh, rsh and rlogin are notoriously bad at security.

HP-UX B.11.23
unfortunately i need a fix in case of remsh and then in future might change to ssh where its working fine ..

USER wouldn't be initialized by any global file -- how could a global file know which user? It should be initialized by the login system, something remsh apparently does an end-run around. You might have to just set it yourself.

Some of the old UNIX did initialize USER from the ownership of the tty. This is where the issue lies. remsh/rsh doesnt allocate a tty, and so cant do this. Other applications that either use "login" or correctly use the PAM method of authorization set default environment variables directly and so dont have this issue.