tcl, regexp matching string

Question

I have problem with my tcl script. In one part of code I grep one string form xml.file containing ipadress (see below), and now I need to match the expression with expect -re i next line, so that I can save it to varible. So I need your help, how to match this, see below what I mean. This is part of code in TCL:

  send -- "cat $filename | grep 'url' \r"
  expect -re "(\<emUrl url=\"(\[0-9]{1,3})\.(\[0-9]{1,3})\.(\[0-9]{1,3})\.(\[0-9]{1,3})\"\/\>\).*ranosusr@rn2osscs603>$"
   set IP $expect_out(1,string)

probelm is that I don't know how to match this experssion, wich is the result of grep:

<emUrl url="10.80.31.123"/>

the ipaddress should be general, because they are different from file to file.

With exp_internal 1 I get this ouput: end: sending "cat FXL704_FRTAMX_SIU_ARNE.xml | grep 'url' \r" to { exp4 }

expect: does "> " (spawn_id exp4) match regular expression "(<emUrl url="(.*)").*ranosusr@rn2osscs603>$"? no
cat FXL704_FRTAMX_SIU_ARNE.xml | grep 'url'

expect: does "> cat FXL704_FRTAMX_SIU_ARNE.xml | grep 'url' \r\r\n" (spawn_id exp4) match regular expression "(<emUrl url="(.*)").*ranosusr@rn2osscs603>$"? no
                  <emUrl url="10.80.31.123"/>

expect: does "> cat FXL704_FRTAMX_SIU_ARNE.xml | grep 'url' \r\r\n                  <emUrl url="10.80.31.123"/>\r\r\n" (spawn_id exp4) match regular expression "(<emUrl url="(.*)").*ranosusr@rn2osscs603>$"? no
ranosusr@rn2osscs603>
expect: does "> cat FXL704_FRTAMX_SIU_ARNE.xml | grep 'url' \r\r\n                  <emUrl url="10.80.31.123"/>\r\r\nranosusr@rn2osscs603> " (spawn_id exp4) match regular expression "(<emUrl url="(.*)").*ranosusr@rn2osscs603>$"? no
expect: timed out

expect: does "> cat FXL704_FRTAMX_SIU_ARNE.xml | grep 'url' \r\r\n                  <emUrl url="10.80.31.123"/>\r\r\nranosusr@rn2osscs603> " (spawn_id exp4) match regular expression "(<emUrl url="([0-9]{1,3}).([0-9]{1,3}).([0-9]{1,3}).([0-9]{1,3})"/>).*ranosusr@rn2osscs603>$"? no
expect: timed out

so take a look at my code, I think maybe some brackets are needed that I can't figure out. Also I have to include ranosusr@rn2osscs603> because this is the server prompt. Please help :)

Donal Fellows · Accepted Answer · 2014-03-16 17:21:54Z

2

As far as I can see (looking at that log, carefully) the main problem with your regular expression is that it contains an End-Of-Text/Line^† anchor ($) yet at no point does the string it is matched against ever contain that; either it doesn't have the text before that anchor in your RE, or it has a space after it. At the very least, try \s$ (well, \\s$) instead so that the space doesn't cause problems.

You might consider using non-greedy REs instead to simplify that RE. Here is what I think would work (without Tcl-syntax backslashes; put it in {braces} to give this to expect without having to inflict backslash-itis on it).

(<emUrl url="(.*?)"/>).*ranosusr@rn2osscs603>\s*$

If you need a reference to the RE language variant supported by Tcl, check out the re_syntax(n) manual page.

^{^† OK, $ is normally an EOT anchor by default, but Expect forces the RE engine to be in EOL mode. This is the Right Thing.}

answered Mar 16, 2014 at 17:21

Donal Fellows

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2 Comments

user3319356 Over a year ago

Hi , I used this template and it's working fine :expect -re {<emUrl url="(.*?)"/>} .....what does command (.*?) replace, is it all what is inside ""?

Donal Fellows Over a year ago

(.*?) does match (and capture) the minimum amount that it can, as opposed to (.*) which captures the maximum. The stuff around it constrains what that minimum is; for this sort of thing, it's often Good Enough even if it isn't actually Formally Correct.

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