[ILUG] Passwordless SSH access

[Niall O Broin]

On Wed, Mar 20, 2002 at 12:11:30AM +0000, Ronan Waide wrote:

> > Yes, Dave gets the banana for sure on that one, provided that that set of ps
> > options work next week/distro/version/whatever :-)
> 
> which is why I prefer my kill -0 option, to be honest.

My ps version works fine, but I was just about to change to the kill -0 way
when I thought of PID reuse - a small error possibility, but definitely
there, so I'm sticking with ps and for that I have a question. There've been
a couple of suggestions of using an RE to grep as in this from Paul

[root at dunlop modules]# ps ax | grep foo
14801 pts/0    S      0:00 grep foo
[root at dunlop modules]# ps ax | grep [f]oo
[root at dunlop modules]#

What is it about grep and RE that causes this behaviour ? (note that the
above example is not always correct. For example, 

niall at bagend:~ >ps -ax|grep [f]oo
 1944 pts/8    S      0:00 grep foo

but if you ensure that grep sees the RE like this
 
niall at bagend:~ >ps -ax|grep "[f]oo"
niall at bagend:~ >

it's fine)

Does grep manipulate its arguments as saved or what ? Because I called my
script ssh-agent-setup I matched on  "$USER.*ssh-agent$" and that works also
(i.e. ps|grep doesn't find the grep) but leaving out the $ doesn't work

james at bilbo:~> ps aux|grep "${USER}.*ssh-agent$"
james     1264  0.0  0.3  2016  740 ?        S    09:16   0:00 ssh-agent
james at bilbo:~> ps aux|grep "${USER}.*ssh-agent"
james     1264  0.0  0.3  2016  740 ?        S    09:16   0:00 ssh-agent
james     1313  0.0  0.3  1612  588 pts/0    S    09:27   0:00 grep james.*ssh-agent
james at bilbo:~>

So, ps|grep won't match the grep when grep uses certain kinds of RE - oh
lordy ! I'm leaving my grep -v grep in, thank you, in case the kind of RE is
dependent on the phase of the moon :-)



Niall