Help with Regexp

[treid71]

Hi all,

I'm having a bit of a problem with a regexp in a tcl script I'm *attempting* to write for my Cisco router.

Long story short, I'm trying to compare the numerical value of the output against a threshold/variable I have set and the script just doesn't want to work. Here is the error I am receiving:

Register event failed:missing close-brace
while compiling
"foreach line [split $output "\n"]"


Here is the section of the script I am having a problem with. I want to extract the "-80" portion of the output and compare it (>=) against the threshold I have set of -75. Many thanks in advance, I have been pulling my hair out on this.


# Setup commands
set command "show cellular 0/2/0 radio | inc RSSI"
# Sample output of above: Current RSSI(RSCP) = -80 dBm


# Pull RSSI stats from router via CLI
set output [run_cli [list $command]]

# Pull out dBm with a regular expression
foreach line [split $output "\n"] {
if { [regexp {.*Current RSSI.* = (.*?)\} $line -> currentdBm] }
if { $currentdBm >= $rssi_signal_threshold }

action_syslog msg "Current RSSI on Cellular 0/2/0 is $currentdBm and has exceeded $rssi_signal_threshold"
}

 

[Bong]

Something's wrong for sure. The error statement implies an unmatched bracket (could be parentheses, square brackets, or braces). It doesn't appear to be a problem on the line noted, foreach line [split $output "\n"] so I'm inclined to suspect that it's an artifact of some previous line. That said, however, I can't make sense of what you have between the {}s of the foreach block.

The foreach structure takes each line of $output successively and applies it to the next three statements. So far so good.

Now, if { [regexp {.*Current RSSI.* = (.*?)\} $line -> currentdBm] } seems to be an if clause with no then. That is, the syntax should be if {hypothetical clause} {conclusion clause}. You have no conclusion.

Moreover, the regexp statement doesn't make sense to me either: [regexp {.*Current RSSI.* = (.*?)\} $line -> currentdBm]. The regexp syntax is regexp <regular expression> <string to match> <match variable> <group variable(s)>. I don't recognize -> as valid Tcl syntax.

_________________
Bob Rashkin

 

[mikrom]

Hi treid71,
Say us exactly, what you want to match and/or extract with a regular expression.

Maybe some of these links how to deal with regular expressions in Tcl help you a little bit:

http://www.tek-tips.com/viewthread.cfm?qid=1515473&page=3

http://www.tek-tips.com/viewthread.cfm?qid=1517450&page=3

http://www.tek-tips.com/viewthread.cfm?qid=1522473&page=2

 

[treid71]

Hi mikrom,

I would like a regexp to extract the number that is in the following string.

Current RSSI(RSCP) = -80 dBm

In this case it is "-80" but it could change depending on the output.

Then I'd like to compare the extracted number to another number (a variable I have set) to see if it is greater than or equal to.



Thanks in advance!

 

[mikrom]

Something like this

[COLOR=#804040][b]set[/b][/color] mystring [COLOR=#ff00ff]"Current RSSI(RSCP) = -80 dBm"[/color]
[COLOR=#804040][b]set[/b][/color] result [[COLOR=#804040][b]regexp[/b][/color] {Current RSSI\s*.*=\s*(-{[COLOR=#ff00ff]0[/color],[COLOR=#ff00ff]1[/color]}\s*\d+)} [COLOR=#008080]$mystring[/color] match number];

[COLOR=#804040][b]if[/b][/color] {[COLOR=#008080]$result[/color]} {
  [COLOR=#804040][b]puts[/b][/color] [COLOR=#ff00ff]"String to apply the pattern: '$mystring'"[/color]
  [COLOR=#804040][b]puts[/b][/color] [COLOR=#ff00ff]"result=$result"[/color]
  [COLOR=#804040][b]puts[/b][/color] [COLOR=#ff00ff]"This was matched: $match"[/color]
  [COLOR=#804040][b]puts[/b][/color] [COLOR=#ff00ff]"Number (extracted): $number"[/color]
} [COLOR=#804040][b]else[/b][/color] {
  [COLOR=#804040][b]puts[/b][/color] [COLOR=#ff00ff]"Nothing matched !"[/color]
}

Output:

C:\Users\Roman\Work>tclsh85 regex.tcl
String to apply the pattern: 'Current RSSI(RSCP) = -80 dBm'
result=1
This was matched: Current RSSI(RSCP) = -80
Number (extracted): -80

 

[treid71]

mikrom - that's exactly what I was looking for. Appreciate the help!