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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 DEBIAN

mz.cfg

mz.cfg(1)						      General Commands Manual							 mz.cfg(1)

NAME

       mz - a fast versatile packet generator

SYNOPSIS

       /etc/mausezahn/mz.cfg

DESCRIPTION

       Mausezahn  is  a free fast traffic generator written in C which allows you to send nearly every possible and impossible packet. Mausezahn's
       MOPS subsystem (Mausezahn's Own Packet System) supports an interactive mode with a Cisco-style command line interface (CLI).  In  order	to
       activate this interactive mode, execute Mausezahn using the -x argument, optionally followed by an arbitrary TCP port number, such as

       # mz -x 99

       in which case you can connect to Mausezahn via

       $ telnet 127.0.0.1 99

       If  no port number is specified, Mausezahn uses the default port number 25542 (which is the date of towel day followed by the answer to the
       universe and everything; however, you don't need to understand this in order to continue).

       Login credentials as well as other MOPS-related parameters can  be  specified  in  the  Mausezahn  configuration  file  mz.cfg  located	in
       etc/mausezahn. Currently, user-specific configuration files are not supported.

       If no configuration file is present Mausezahn assumes the following default login credentials:

	      username: mz
	      password: mz
	      enable password: mops

       Currently only login credentials can be configured within the configuration file. Here is an example content of /etc/mausezahn/mz.cfg:

	      user = herbert
	      password = moTTe
	      enable = T0p5ecreT

       Additional configuration options will be officially supported with the next releases.

FILES

       /etc/mausezahn/mz.cfg

SEE ALSO

	mz(1)

AUTHOR

       Herbert Haas.

       Visit www.perihel.at/sec/mz/ for Mausezahn news and additional information.

       This manual page was written by Herbert Haas <herbert AT perihel DOT at>, for the Debian project.

								   March 7, 2010							 mz.cfg(1)
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