expect: line seems to match exactly, however expect thinks not

deadeyes · 06-16-2010, 11:03 AM

Hi all,

I am writing an expect script.

At a certain point there is a rule that produces this debugging output:

Code:

expect: does "\r\nAddress or name of remote host [x.x.x.x]? " (spawn_id exp8) match glob pattern "\r\nAddress or name of remote host [x.x.x.x]? "? no

This just times out :s

When I use -exact for the expect keyword it does work :s
What am I doing wrong? THe first should also match in my opinion because it is equal as well. Even if I remove the \r\n I still have the same issue if I try without -exact.

I don't understand. I tried removing the \r\n but still got the same.

Anyone an idea on what the issue might be?

ilikejam · 06-16-2010, 11:51 AM

Hi.

TCL's and expect's glob patterns use [] for ranges, so it's probably the '[x.x.x.x]' that's tripping it up. Try matching \[x.x.x.x] or \\[x.x.x.x] instead. The '?' should be escaped as well, but since it's the wildcard for any single character, it shouldn't be causing the problem you're seeing.

Dave

deadeyes · 06-16-2010, 03:30 PM

Thanks for your quick response.

I have this in the expect file:

Code:

expect {
      "\r\nAddress or name of remote host \[[lindex $argv 3]\]? " { send -- "\r"; exp_continue }
      ...
}

So these are already escaped.

Edit:
I also tried using:
set myvar [lindex $argv 3]
and then use $myvar in the line but that results in the same issue.

ilikejam · 06-16-2010, 05:25 PM

Ah, the layers of indirection.

Believe it or not, triple-escaping the first [ should do the job

Code:

expect {
      "\r\nAddress or name of remote host \\\[[lindex $argv 3]\]? " { send -- "\r"; exp_continue }
      ...
}

Dave

deadeyes · 06-16-2010, 05:54 PM

Lol...

that fixed it indeed!

However I wonder why. \\ seems logical. \\\ doesn't

Maybe there are two passes of the part between quotes but that does not explain why the closing ] does not need this.

THanks alot for helping me out!

ilikejam · 06-16-2010, 06:05 PM

There are indeed two passes. expect eats one of the \'s, then tcl eats the second \ before the string is used as a glob. The second ] doesn't actually need /any/ escape for this to work, though - feel free to remove it.

Dave