Problem with Substring Post: 302252555

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Top Forums Shell Programming and Scripting Problem with Substring Post 302252555 by cfajohnson on Wednesday 29th of October 2008 08:24:29 PM

10-29-2008

Registered User

Quote:

Originally Posted by manmeet

Hi,
i have a file from which i extracted 2nd column and put it into a variable Acct_Num . Now i need to extract first 3 digits from it and save in to other variable.
My Code is:

Please put code inside [code] tags.

Quote:

Code:

 
  while read Record1
do
 Acct_Num=`echo $Record1 | awk '{print $2 }'`
 ID=`echo $Record1 | awk '{print substr($Acct_Num, 1, 3 ) }`

The immediate problem is that a shell variable is not expanded inside single quotes. You can pass a variable to awk with -v:
Code:
awk -v Acct_Num="$Acct_Num" '{print substr(Acct_Num, 1, 3 ) }'
The other problem is that your script will run excruciatingly slowly because you are calling awk twice for every line of the file.

Instead of using a shell loop, let awk do all the work:
Code:
awk '{
  printf "AcctNum is %s\n", $2
  printf "ID is %s\n", substr($2,1,3)
   }' "$REGSeqFileName"

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LEARN ABOUT REDHAT

igawk

IGAWK(1)							 Utility Commands							  IGAWK(1)

NAME

       igawk - gawk with include files

SYNOPSIS

       igawk [ all gawk options ] -f program-file [ -- ] file ...
       igawk [ all gawk options ] [ -- ] program-text file ...

DESCRIPTION

       Igawk is a simple shell script that adds the ability to have ``include files'' to gawk(1).

       AWK programs for igawk are the same as for gawk, except that, in addition, you may have lines like

	      @include getopt.awk

       in your program to include the file getopt.awk from either the current directory or one of the other directories in the search path.

OPTIONS

       See gawk(1) for a full description of the AWK language and the options that gawk supports.

EXAMPLES

       cat << EOF > test.awk
       @include getopt.awk

       BEGIN {
	    while (getopt(ARGC, ARGV, "am:q") != -1)
		 ...
       }
       EOF

       igawk -f test.awk

SEE ALSO

       gawk(1)

       Effective AWK Programming, Edition 1.0, published by the Free Software Foundation, 1995.

AUTHOR

       Arnold Robbins (arnold@skeeve.com).

Free Software Foundation					    Nov 3 1999								  IGAWK(1)

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