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Full Discussion: Just need some guidance on this nawk
Top Forums UNIX for Dummies Questions & Answers Just need some guidance on this nawk Post 302827485 by newbie_01 on Friday 28th of June 2013 09:04:42 PM
Old 06-28-2013
Just need some guidance on this nawk
Hi,

I am trying to debug some KSH script and it has the nawk portion below. I just want to confirm whether I understand what it does correctly.

Example usage of the nawk line is run as below:

Code:
 
nawk '/^#/ {next}
$1~/^'testp.cfg'$|^'testp.cfg'\.testdb\.com\.ph$/ {
   c=0
   while (getline) {
     gsub (" ","")
     s=tolower($0)
     if (s~/host=/) {
        sub("^.*host=","",s)
        sub("\\\).*","",s)
        print s
        exit
     }
     c++
     if (c>20) {exit}
   }
}' $TNSNAMES

$TNSNAMES is a tnsnames.ora file, excerpts of some of its lines as below:

Code:
 
testd.testdb.com.ph = 
  (DESCRIPTION = 
        (ADDRESS = 
          (COMMUNITY = tcpip.world)
          (PROTOCOL = TCP)
          (Host = testd.testdb.com.ph)
          (Port = 25036)
        )
      (CONNECT_DATA = 
        (SID = testd)
           (GLOBAL_NAME = testd.testdb.com.ph)
      )
  )
testp.cfg = 
  (DESCRIPTION = 
        (ADDRESS = 
          (COMMUNITY = tcpip.world)
          (PROTOCOL = TCP)
          (Host = testp1)
          (Port = 5000)
        )
      (CONNECT_DATA = 
        (SID = testp)
           (GLOBAL_NAME = testp.cfg)
      )
  )

From what I understand, the nawk excludes all lines that begins with a # and if it finds a line that begins with testp.cfg or testp.cfg.testdb.com.ph, and starting from that line, it reads a line, strips the spaces, and convert it to lower case. Now I don't understand what this section of the nawk does?


Code:
     if (s~/host=/) {
        sub("^.*host=","",s)
        sub("\\\).*","",s)
        print s
        exit
     }
     c++
     if (c>20) {exit}


Does the first sub strips all spaces before the host= string? But what does the second sub do? Remove everything from the first dot (.)?

Is the c variable means it will only process 20 lines from when it find the testp.cfg or testp.cfg.testdb.com.ph string?

Any feedback much appreciated. Thanks in advance.
 

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LEARN ABOUT OPENSOLARIS

ser.cfg

ser.cfg(5)							Sip Express Router							ser.cfg(5)

NAME

       ser.cfg - ser configuration file

SYNOPSIS

       /etc/sfw/ser/ser.cfg

DESCRIPTION

       ser  reads  the configuration data from /etc/sfw/ser/ser.cfg (or the file specified with -f on the command line).  The file contains global
       configuration parameters, module loading commands and the script that will be executed for each received request. Lines starting with #	or
       enclosed in /* ... */ are interpreted as comments.

       This manual page is incomplete. For further information please read the Ser User Guide (http://www.iptel.org/ser/admin.html).

FILES

       /etc/sfw/ser/ser.cfg

AUTHORS

       Andrei Pelinescu - Onciul, <pelinescu-onciul@fokus.gmd.de>
       Bogdan Andrei Iancu
       Daniel-Constantin Mierla
       Jan Janak
       Jiri Kuthan
       Juha Heinanen
       Maxim Sobolev
       Miklos Tirpak
       Nils Ohlmeier
       Ramona-Elena Modroiu
       Raphael Coeffic
       Ricardo Baratto
       Stelios Sidiroglou-Douskos

SEE ALSO

       ser(8)

       Full documentation on ser, including configuration guidelines, FAQs and licensing conditions, is available at http://www.iptel.org/ser/.

       For reporting  bugs see http://www.iptel.org/ser/bugs/.

       Mailing lists:
       serusers@iptel.org - ser user community
       serdev@iptel.org - ser development, new features and unstable version

       For help/support, write an email to <serhelp@iptel.org>.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +--------------------+--------------------+
       |  ATTRIBUTE TYPE    |  ATTRIBUTE VALUE	 |
       +--------------------+--------------------+
       |Availability	    | SUNWserr, SUNWseru |
       +--------------------+--------------------+
       |Interface Stability | External		 |
       +--------------------+--------------------+
NOTES

       Source for ser is available on http://opensolaris.org.

ser								    15.07.2002								ser.cfg(5)
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