Top Forums Shell Programming and Scripting Don't understand how RS functions in awk Post 302449029 by joe228 on Friday 27th of August 2010 11:31:47 PM
Don't understand how RS functions in awk

I learn using RS in awk to extract portion of file in this forum which is wonderful solution to the problem. However, I don't understand how exactly it operates.

I don't quite understand the mechanism behind how searching for /DATA2/ can result in extracting the whole section under "DATA2"




$cat sample | awk 'BEGIN {RS=""} /DATA2/'

Since RS is set to be empty string, so each line now should be regarded as a field and so I expected printing $1 and $2 would give me the output of DATA1 and data11 but it didn't. Instead, it returned me with what is shown below:

$ cat sample | awk 'BEGIN {RS=""} { print $1 }'
$ cat sample | awk 'BEGIN {RS=""} { print $2 }'

So, can someone explain to me why it behaved this way?? Thanks!

Moderator's Comments:
Mod Comment Please use code tags, thank you!

Last edited by Franklin52; 08-28-2010 at 10:14 AM..
Test Your Knowledge in Computers #559
Difficulty: Easy
A runtime error is an error that occurs while a program is being executed.
True or False?

8 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

don't understand the unix script

if {"$my_ext_type" = MAIN]; then cd $v_sc_dir Filex.SH $v_so_dir\/$v_fr_file Can somebody tell me what does this suggest. I am pretty new to unix and I am getting confused. What i understood from here is If we have a file extension name as MAIN which we have then we change the directory to... (1 Reply)
Discussion started by: pochaman
1 Replies

2. Homework & Coursework Questions

I don't understand some basics..

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted! 1. The problem statement, all variables and given/known data: 1)find all lines in file ,myf that contain all the words cat dog and mouse in any order and start with the letter... (1 Reply)
Discussion started by: cudders
1 Replies

3. UNIX for Dummies Questions & Answers

Another Simple BASH command I don't understand. Help?

I have a text file called file1 which contains the text: "ls -l" When I enter this command: bash < file1 > file1 file1 gets erased. However if I enter this command: bash < file1 > newfile the output from "ls -l" is stored in newfile. My question is why doesn't file1's text ("ls -l") get... (3 Replies)
Discussion started by: phunkypants
3 Replies

4. Shell Programming and Scripting

Perl syntax that I don't understand.

I'm just trying to confirm that I understand someone's code correctly. If someone has code that says: $foo ||= mysub(); I'm assuming that it means if $foo is nothing or undef, then assign it some value via mysub(). If I'm wrong on this, please let me know. Also, what's the difference... (4 Replies)
Discussion started by: mrwatkin
4 Replies

5. UNIX for Dummies Questions & Answers

trying to compile and don't understand error message

this is my program i am trying to compile /* filedata -- display information about a file */ #include <stdlib.h> #include <stdio.h> #include <sys/stat.h> #include <sys/types.h> /* * use octarray for determing * if permission bits set */ static short octarray = {0400, 0200, 0100,... (2 Replies)
Discussion started by: heywoodfloyd
2 Replies

6. UNIX for Dummies Questions & Answers

I don't understand conditions :(

Hi there, I have a very general question. I'm rather new to (bash) shell scripting and I don't understand how conditions work... I've read numerous tutorials but I don't get it. I really don't. Sometime what I do works, sometime it doesn't and that's frustating. So what's the actual difference... (0 Replies)
Discussion started by: hypsis
0 Replies

7. Programming

Understand Virtual functions Internals

I am just trying to understand the virtual fns. concept. I know that if I have a virtual fn. in a base class and its overridden fn. in derived class then based upon the address of base/derived object stored in the base class pointer the fns. will be called. In the below code I had kept... (2 Replies)
Discussion started by: rupeshkp728
2 Replies

8. Shell Programming and Scripting

Don't understand AWK asort behaviour

Hello, I have the following script : BEGIN { print "1 ***"; split("abc",T,""); T="e"; T="z"; T="y"; for (i in T) printf("%i:%s ",i,T); print ""; for (i=1; i<=length(T); i++) printf(T); print "" print "2 ***"; asort(T,U); for (i in U) printf("%i:%s ",i,U); ... (3 Replies)
Discussion started by: jgilot
3 Replies
IGAWK(1)							 Utility Commands							  IGAWK(1)

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 ( ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWgawk | +--------------------+-----------------+ |Interface Stability | Volatile | +--------------------+-----------------+ NOTES
Source for gawk is available on Free Software Foundation Nov 3 1999 IGAWK(1)

Featured Tech Videos

All times are GMT -4. The time now is 03:40 PM.
Unix & Linux Forums Content Copyright 1993-2020. All Rights Reserved.
Privacy Policy