From: Dale Martenson <devlists-ruby-talk@...>
Date: 2006-07-29T00:44:44+09:00
Subject: Double quotes embedded in a string ...

Here is something that I am struggling with -- I would like to execute a  
command string with an IO.popen call that contains embedded double quote  
characters. When I build the initial command string everything seems to  
work, but once I pass is on to IO.popen, it seems to mess up the double  
quotes.

Here is my example, I want to execute the following command from a Ruby  
program:

     pppd connect "chat -v '' ATZ OK ATDT5551234 CONNECT '' ogin:  
username word: password" /dev/ttyS0 115200 -detach crtscts modem defaultroute

I create the command string by the long and somewhat ugly ruby command:

     command = "pppd connect \\\"chat -v '' #{initialization_command}  
#{initialization_response} #{dial_command} #{dial_response} ''  
#{username_prompt} #{username} #{password_prompt} #{password}\\\"  
#{device.name} #{speed} -detach crtscts modem defaultroute\r\n"

In this case, I escaped the escaped the double quote. I have also tried  
various combinations of multiple double quotes (4 in a row, etc.).

If I now echo the command using a system call:

     system( "echo #{command}" )

the command seems to echo the desired result:

     pppd connect "chat -v  ATZ OK ATD5551234 CONNECT  ogin: username  
word: password" /dev/ttyS0 115200 -detach crtscts modem defaultroute

But when I pass it to IO.popen, I get

     pppd: unrecognized option '-v'
     pppd version 2.4.1
       Usage: pppd [ options ], where options are:
             <device>        Communicate over the named device
             <speed>         Set the baud rate to <speed>
             <loc>:<rem>     Set the local and/or remote interface IP
                             addresses.  Either one may be omitted.
             asyncmap <n>    Set the desired async map to hex <n>
             auth            Require authentication from peer
             connect <p>     Invoke shell command <p> to set up the  
serial line
             crtscts         Use hardware RTS/CTS flow control
             defaultroute    Add default route through interface
             file <f>        Take options from file <f>
             modem           Use modem control lines
             mru <n>         Set MRU value to <n> for negotiation
     See pppd(8) for more options.

which is caused by that the double quotes are being stripped by  
IO.popen. How do I avoid this?

Thanks,
Dale Martenson
-- 
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