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Full Discussion: bash: need to have egrep to return a text string if the search pattern has NOT been found
Top Forums Shell Programming and Scripting bash: need to have egrep to return a text string if the search pattern has NOT been found Post 302669263 by bash4ever on Tuesday 10th of July 2012 07:14:08 PM
Old 07-10-2012
bash: need to have egrep to return a text string if the search pattern has NOT been found
Hello all,

after spending hours of searching the web I decided to create an account here. This is my first post and I hope one of the experts can help.

I need to resolve a grep / sed / xargs / awk problem.

My input file is just like this:

----------------------------------
Code:
root@Ubuntu-12:~# cat myfile 
article1
data.........x
colour....blue
number.........15
name...smith
month...................july

article2
colour....yellow
number.........423489
something....x
month...................january

article3
colour....orange
number.........7
name....jason
month...................may
value.....4
much
more
lines
root@Ubuntu-12:~#

----------------------------------

This is the code I currently use (example):
Code:
grep "^article[0-9]$" -A5 myfile | while read x ; do echo "$x" | egrep "article|colour|number|name|month" | \
awk -F . '{print $NF}' ; done | xargs -L5 | \
awk 'BEGIN {printf("%15s %15s %15s %15s %15s\n" ,"Article", "Colours", "Numbers", "Names", "Month")} {printf("%15s %15s %15s %15s %15s\n", $1, $2, $3, $4, $5)}'

Unfortunately the output looks like this:
Code:
        Article         Colours         Numbers           Names           Month
       article1            blue              15           smith            july
       article2          yellow          423489         january        article3
         orange               7           jason             may

As we can see the format is screwed up because we are egrep'ping for 5 values. This was successful for "article1" but "name...xx" is missing in "article2". Therefore "article3" is used as the 5th column in row 2 rather than in column1 of row 3.

So xargs is parsing the wrong format into awk which eventually shifts the table:
Code:
grep "^article[0-9]$" -A5 myfile | while read x ; do echo "$x" | egrep "article|colour|number|name|month" | awk -F . '{print $NF}' ; done | xargs -L5

Code:
article1 blue 15 smith july
article2 yellow 423489 january article3
orange 7 jason may

------------------------------------

Now the question. Is there a way that egrep, when searching for 5 strings but only finding 4, is replacing a missing string with a replacement word like "missing"? This would ensure xargs -L5 is happy and awk keeps the format for the table.

Or is there a more efficient way of doing this?

The input text file is just an example for a much larger file with hundreds of thousands of lines.
Last edited by methyl; 07-10-2012 at 09:41 PM.. Reason: code tags on the data ; break very long lines; more code tags; somehow get this post readable
 

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