Is it better to grep and pipe to awk, or to seach with awk itself Post: 302243983

Sponsored Content

Top Forums Shell Programming and Scripting Is it better to grep and pipe to awk, or to seach with awk itself Post 302243983 by cfajohnson on Tuesday 7th of October 2008 01:43:34 AM

10-07-2008

Registered User

Quote:

Originally Posted by DeCoTwc

This may just be a lack of experience talking, but I always assumed that when possible it was better to use a commands built in abilities rather than to pipe to a bunch of commands. I wrote a (very simple) script a while back that was meant to pull out a certain error code, and report back what piece of equipment had thrown it:

Code:

#!/usr/bin/bash
######################################################
# Program:      problemboxes.sh 
# Date Created: 14 May 2008
# Developer:    Darrell S. **** (Digital Sys. Admin)
# Description:  Generates lists of boxes that have thrown excess error 18's 
# Last Updated: 7 Aug 2008
######################################################
clear
user=`echo $UID`

Why are you using command substitution instead of a straight assignment? In all shells except ksh93, it forks a new process and is almost as slow as an external command. Use:
Code:
user=$UID

Quote:

[snip]

What seems odd to me is, that while both return the same results, the one that searches with awk, takes considerably longer (granted only ~3 seconds right now, but that's because the log rolled at midnight) than the one that uses grep.

The search code in grep is much faster than that in all versions of awk except mawk, but it will not make much difference except on very large files.

The authors of AWK, in their book, The AWK Programming Language, recommend using grep to search and piping the results though awk for processing rather than doing it all in AWK.

cfajohnson

View Public Profile for cfajohnson

Find all posts by cfajohnson

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

AWK seach for exact word in certain column

Can anyone help me how I will extract all lines in a file where the word "worker" or "co-worker" in 2nd column exist. There are also word in 2nd column like "workers" or "worker2" but I don't want to display those lines. Appreciate any help in advance! Thank you!

2. Shell Programming and Scripting

pipe'ing grep output to awk

This script is supposed to find out if tomcat is running or not. #!/bin/sh if netstat -a | grep `grep ${1}: /tomcat/bases | awk -F: '{print $3}'` > /dev/null then echo Tomcat for $1 running else echo Tomcat for $1 NOT running fi the /tomcat/bases is a file that...

3. Shell Programming and Scripting

Read content between xml tags with awk, grep, awk or what ever...

Hello, I trying to extract text that is surrounded by xml-tags. I tried this cat tst.xml | egrep "<SERVER>.*</SERVER>" |sed -e "s/<SERVER>$.*$<\/SERVER>/\1/"|tr "|" " " which works perfect, if the start-tag and the end-tag are in the same line, e.g.: <tag1>Hello Linux-Users</tag1> ...

4. Shell Programming and Scripting

Pipe to awk to variable

Hi! If I'm trying something like: echo "hello world" | myvar=`awk -F "world" '{print $1}'` echo $myvar myvar is always empty :confused: I googled for houres now and don't understand why it isn't working... Trying it in normal bash. Can someone explain it to me so I can say "Of course!...

5. Shell Programming and Scripting

help with sed or awk with less pipe

<tr><th align=right valign=top>Faulty_Part</th><td align=left valign=top>readhat version 6.0</td></tr> <tr><th align=right valign=top>Submit_Date</th><td align=left valign=top>2011-04-28 02:08:02</td></tr> .......(a long string) I want to get all the field between "left valign=top>" and "...

6. Shell Programming and Scripting

Find files and seach limit with grep

Hi, I'm testing nginx-cache-purge and notice that grep searches all file content, and since the cache key is in the second line I would like to limit grep searching. This is the script I'm using: github.com/perusio/nginx-cache-purge The line I would like to change and limit grep search...

7. Shell Programming and Scripting

awk print pipe

Hey fellas, I wrote an script which its output is like this: a 1 T a 1 T a 2 A b 5 G b 5 G b 5 G I wanna print $1 $2 and the total number of $2 value as the third column and after that $3. Sth like this: a 1 2 T a 2 1 A b 5 3 G I know how to do it with a given input...

8. Shell Programming and Scripting

Use less pipe for grep or awk sed to print the line not include xx yy zz

cat file |grep -v "xx" | grep -v "yy" |grep -v "zz"

9. Shell Programming and Scripting

awk seach and printing a particular pattern

Hi i need a help for this. the output of a command is like below 1 /tmp/x 2.2K /tmp/y 3.2k /tmp/z 1G /tmp/a/b 2.2G /tmp/c 3.4k /tmp/d Now i need to grep for the paths which are in GB..like below 1G /tmp/a/b 2.2G /tmp/c pls suggest me, how can i...

10. Shell Programming and Scripting

awk pipe to sort

In the below awk to add a sort by smallest to largest should it be added after the END? Thank you :). BEGIN { FS="*" } # Read search terms from file1 into 's' FNR==NR { s next } { # Check if $5 matches one of the search terms for(i in s) { if($5 ~ i) { ...

LEARN ABOUT LINUX

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)