Re: [Expectperl-discuss] expect output split into pieces

[Ken I. <fn...@ua...>]

On Thu, May 17, 2007 at 11:53:52AM -0700, Jason Gerdes wrote:
> Hello,
> 
> Here is the problem I am having:
> 
> I use expect to spawn an SSH session to a cisco router and run the
> command 'show arp', which sends a lot of data back.  example:
> 
> gw>show arp
> Protocol  Address          Age (min)  Hardware Addr   Type   Interface
> Internet  XX.XX.108.17            0   XXXX.319f.c3d9  ARPA   Vlan133
> Internet  XX.XX.97.28           171   XXXX.c525.d4c3  ARPA   Vlan122
> Internet  XX.XX.99.30            41   XXXX.420c.e73f  ARPA   Vlan124
> ... (there are thousands of lines sent back)
> 
> The problem I get is that expect seems to process this data in chunks.
> For example, it will process:
> 
> Protocol  Address          Age (min)  Hardware Addr   Type   Interface
> Internet  XX.XX.108.17            0   XXXX.319f.c3d9  ARPA   Vlan133
> Internet  XX.XX.97.28           171   XXXX.c5
> 
> where it will pull out the data correctly for the first line, but will
> not match the second line since it is incomplete.  Then, it processes
> the next chunk.  example:
> 
> 25.d4c3  ARPA   Vlan122
> Internet  XX.XX.99.30            41   XXXX.420c.e73f  ARPA   Vlan124
> 
> where it will not pull the data correctly for the first line
> (incomplete), but will pull the correct data for the second line.
> 
> I have used the TCL expect before and it does the same thing so I know
> it is not a bug.  I think there is just a gap in my understanding of
> how expect processes the data that is sent back from spawned processes.
> 
> Is there a way to make expect deal with all of the data as one big
> chunk, rather than processing it in pieces?  I hope someone can explain
> how this works.

If you "expect" some string or pattern that appears only after the
desired output is complete, e.g., perhaps the command prompt "gw>",
everything ought to be found in the before() method.

-- 
Ken Irving