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Printing null values in awk

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# 1  
Old 11-04-2016
Printing null values in awk
Hi,

I have a csv file with given details
abc.txt
Code:
123,ra,point,,there
232,ba,points,home,pheer

I want to get those values and store them in different variables:

Code:
Code:
while read line
do
echo $line |awk -F"," '{print $1" "$2" "$3" "$4" "$5"}'|read dbt_acct val_dt crncy AMT dbt_GOP
print $AMT
done <abc.txt

Required Output:
Code:
home

But the output I am getting is:
Code:
there
home

# 2  
Old 11-04-2016
Try:
Code:
while IFS=, read -r dbt_acct val_dt crncy AMT dbt_GOP
do      
        print "$AMT"
done <abc.txt

This User Gave Thanks to Don Cragun For This Post:
rahulsk
# 3  
Old 11-04-2016
This works because the fourth field of the first line is empty; that loop prints the empty string "" immediatedly followed by "home". With any string in he first line's fourth field it would print
"any stringhome"
If you really want to print the second line's fourth field ONLY, try
Code:
{ IFS=, read; IFS=, read -r X X X AMT X; printf "%s\n" "$AMT"; } < abc.txt
home

This User Gave Thanks to RudiC For This Post:
rahulsk
# 4  
Old 11-04-2016
Quote:
Originally Posted by RudiC
This works because the fourth field of the first line is empty; that loop prints the empty string "" immediatedly followed by "home". With any string in he first line's fourth field it would print
"any stringhome"
If you really want to print the second line's fourth field ONLY, try
Code:
{ IFS=, read; IFS=, read -r X X X AMT X; printf "%s\n" "$AMT"; } < abc.txt
home

Hi RudiC,

Thanks for the details..
Can you please help me in knowing what is the problem in the code what I have written?

---------- Post updated at 05:03 PM ---------- Previous update was at 04:33 PM ----------

Quote:
Originally Posted by Don Cragun
Try:
Code:
while IFS=, read -r dbt_acct val_dt crncy AMT dbt_GOP
do      
        print "$AMT"
done <abc.txt


Hi Don,

Thanks for the command.

Can you please help me in knowing what is the problem in the code what I have written?
Last edited by rahulsk; 11-04-2016 at 08:31 AM..
# 5  
Old 11-04-2016
in awk, you could try

Code:
awk -F, '$4 != "" {print $4}' file

awk reads line based so no need to go for while loop and awk.
Just use while as Don & RudiC shared or just awk as mentioned above.

Quote:
Can you please help me in knowing what is the problem in the code what I have written?
I dont think your command output instead it should error due to following:
Code:
echo $line |awk -F"," '{print "$1" "$2" "$3" "$4" "$5"}'|read dbt_acct val_dt crncy AMT dbt_GOP

Code:
print $AMT

# 6  
Old 11-04-2016
I assume you are using ksh, because in other shells (e.g. bash), piped commands are executed in subshells whose variables are not conveyed back to the parent, so $AMT would not be defined. On top, ksh's print builtin is not generally known in other shells.

You code has two problems:
- the double quote after $5 is unpaired, i.e. it opens but doesn't close a string
- when printing an empty variable between default OFS (space), awk outputs two spaces that are interpreted as just one field delimiter by the followingread, thus advancing "there" into fourth field.
This User Gave Thanks to RudiC For This Post:
greet_sed
# 7  
Old 11-04-2016
Hi,
In bash with pipeline work under many conditions, just a silly example to present bash pipeline:
In general, not work by default:
Code:
$ while read line; do echo $line | IFS="," read dbt_acct val_dt crncy AMT dbt_GOP ; echo $AMT; done <abc.txt 


$

man bash says:
Quote:
lastpipe
If set, and job control is not active, the shell runs the last command of a pipeline not executed in the background in the current
shell environment.
So, set lastpipe option:
Code:
$ shopt -s lastpipe

disable job control:
Code:
$ set +m

Now, it works:
Code:
$ while read line; do echo $line | IFS="," read dbt_acct val_dt crncy AMT dbt_GOP ; echo $AMT; done <abc.txt 

home

Regards.
These 2 Users Gave Thanks to disedorgue For This Post:
rahulsk RudiC
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