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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

py2dsc

PY2DSC(1)							   User Commands							 PY2DSC(1)

NAME

       py2dsc - creates Debian source package from Python package

DESCRIPTION

       usage: py2dsc [options] distfile

	      or: py2dsc --help

       where distfile is a .zip or .tar.gz file built with the sdist command of distutils.

OPTIONS

       --dist-dir (-d)
	      directory to put final built distributions in (default='deb_dist')

       --patch-already-applied (-a)
	      patch was already applied (used when py2dsc calls sdist_dsc)

       --default-distribution
	      deprecated (see --suite)

       --suite (-z)
	      distribution name to use if not specified in .cfg (default='unstable')

       --default-maintainer
	      deprecated (see --maintainer)

       --maintainer (-m)
	      maintainer name and email to use if not specified in .cfg (default from setup.py)

       --extra-cfg-file (-x)
	      additional .cfg file (in addition to stdeb.cfg if present)

       --patch-file (-p)
	      patch file applied before setup.py called (incompatible with file specified in .cfg)

       --patch-level (-l)
	      patch file applied before setup.py called (incompatible with file specified in .cfg)

       --patch-posix (-q)
	      apply the patch with --posix mode

       --remove-expanded-source-dir (-r)
	      remove the expanded source directory

       --ignore-install-requires (-i)
	      ignore the requirements from requires.txt in the egg-info directory

       --pycentral-backwards-compatibility
	      This option has no effect, is here for backwards compatibility, and may be removed someday.

       --workaround-548392
	      This option has no effect, is here for backwards compatibility, and may be removed someday.

       --force-buildsystem
	      If True, pass '-- buildsystem=python_distutils' to dh sequencer

       --no-backwards-compatibility
	      This option has no effect, is here for backwards compatibility, and may be removed someday.

       --guess-conflicts-provides-replaces
	      If True, attempt to guess Conflicts/Provides/Replaces in debian/control based on apt-cache output. (Default=False).

py2dsc 0.6.0+20100620						     May 2011								 PY2DSC(1)
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