Re: more ?s WHOOPS!!!!!

[Peter Paluch <peterp@frcatel.utc.sk>]

Hello friends,
==============

john@dhh.gt.org wrote:

> The single quotes are suffient to protect the '$' from the shell.  The '\'
> is harmless but unnecessary as '$' is not special to chat.  In this case
> chat just eats the '\', determines the the '$' is not one of its special
> characters, sends the '$', and proceeds.  I do not recommend relying on
> this behavior however, since it is undocumented.  Chat could just as well
> eat non-special characters preceeded by a '\'.

Ehm... This is true. I tried the chat on the command line and it works
just fine. However, if someone tries to run chat within pppd (parameter
"connect") without '\', it goes awry. Here, have a look at this:

I type this command:

knm:~# pppd /dev/ttyS0 connect "chat -v '' 'at$n=1' OK"

And this is what I found in /var/log/ppp.log:

Feb 15 19:12:07 knm pppd[494]: pppd 2.2.0 started by root, uid 0
Feb 15 19:12:08 knm chat[495]: send (at=1^M) 
Feb 15 19:12:08 knm chat[495]: expect (OK) 
Feb 15 19:12:08 knm chat[495]: at=1^M^M      ##### <--- see that ?!
Feb 15 19:12:08 knm chat[495]: OK -- got it 

However, if I try this command:

knm:~# pppd /dev/ttyS0 connect "chat -v '' 'at\$n=1' OK"

it is correct then:

Feb 15 19:13:40 knm pppd[502]: pppd 2.2.0 started by root, uid 0
Feb 15 19:13:41 knm chat[503]: send (at$n=1^M) 
Feb 15 19:13:41 knm chat[503]: expect (OK) 
Feb 15 19:13:41 knm chat[503]: at$n=1^M^M 
Feb 15 19:13:41 knm chat[503]: ERROR^M 

My modem doesn't know the $n directive so it returns ERROR, that's fine.

As I do not use pon and poff scripts (maybe I should, what do you
think?), rather call pppd directly, I have to use multiple-backslash
convention ;-) Number of backslashes used is mostly empirically guessed
:)


Thanks for making my knowledges wider ;-)

Everything the best,
Peter
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