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Top Forums Shell Programming and Scripting Awk regular expression - I need exactly 1 occurrence of it Post 302274271 by ioannisp on Wednesday 7th of January 2009 06:12:30 AM
Old 01-07-2009
Thanx everybody for replying.

The problem was not solvedSmilie

It seems that the second part of the expression

$1~/[0-9]\.(0|5)/ && ...2nd part...

is always true if the first part is true. Whether the expression is "!a[substr($1,1,3)]++" or "!a[$0]".

The solution frostmourn suggested unfortunately didn't compile and I am afraid I don't understand the structure that well in order to make it compile.

Just for the record, the actuall file looks like this (I posted a simplified view before, thought it didn't matter):

"
+ 0.1 0 1 tcp 40 ------- 1 0.0 6.0 0 0
- 0.1 0 1 tcp 40 ------- 1 0.0 6.0 0 0
+ 0.1 7 2 tcp 40 ------- 2 7.0 6.1 0 1
- 0.1 7 2 tcp 40 ------- 2 7.0 6.1 0 1
+ 0.1 8 3 tcp 40 ------- 3 8.0 6.2 0 2
- 0.1 8 3 tcp 40 ------- 3 8.0 6.2 0 2
...
...
- 12.999072 2 7 ack 40 ------- 2 6.1 7.0 59 1228
r 13.002496 2 7 ack 40 ------- 2 6.1 7.0 59 1227
r 13.015712 3 2 ack 40 ------- 2 6.1 7.0 59 1229
+ 13.015712 2 7 ack 40 ------- 2 6.1 7.0 59 1229
- 13.015712 2 7 ack 40 ------- 2 6.1 7.0 59 1229
r 13.019136 2 7 ack 40 ------- 2 6.1 7.0 59 1228
r 13.035776 2 7 ack 40 ------- 2 6.1 7.0 59 1229
"

and the '$1' in my previous example is the '$2' in the actual problem. So this is the code I use based on your suggestions (I also need $1 to be "r", $3 to be 1 and $5 to be "tcp" but it doesn't change anything):

if($1=="r" && ($2~/\.(0|5)/ && !a[substr($2,1,3)]++) && $3==1 && $5=="tcp")
{
...
}

this didn't work either:
if($1=="r" && ($2~/\.(0|5)/ && !a[$2]) && $3==1 && $5=="tcp")
{
...
}

still doing something wrong?Smilie

//The code I used before and returned all the occurences and not just the first one was:
if($1=="r" && ($2~ /\.0/ ||$2~ /\.5/) && $3==2 && $5=="tcp")
{
...
}

Thanx in advance.


@rujuta_rahalkar: substr(a,b,c) returns a substring of the string a, that begins at place b (starting from 1) and extends to c places. The effects of the negation and the increment are not clear to me either.

Last edited by ioannisp; 01-07-2009 at 07:48 AM..
 

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tcp-env(1)                                                    General Commands Manual                                                   tcp-env(1)

NAME
tcp-env - set up TCP-related environment variables SYNOPSIS
tcp-env [ -rR ] [ -ttimeout ] program [ arg ... ] DESCRIPTION
The input for tcp-env must be a TCP connection. tcp-env finds out information about that connection, puts the information into several environment variables as described in tcp-environ(5), and runs program with the given arguments. Usually tcp-env is run from inetd. It might instead be run from another server that already sets up the right environment variables; if PROTO is set to TCP when tcp-env is invoked, tcp-env assumes that all the other variables are set up properly, and it does not check whether the input is a TCP connection. OPTIONS
-r (Default.) Attempt to obtain TCPREMOTEINFO from the remote host. -R Do not attempt to obtain TCPREMOTEINFO from the remote host. -ttimeout Give up on the TCPREMOTEINFO connection attempt after timeout seconds. Default: 30. SEE ALSO
tcp-environ(5), inetd(8) tcp-env(1)
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