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Testing Next Record before processing is done on that Record


 
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# 1  
Old 10-15-2009
Testing Next Record before processing is done on that Record

I am trying to see if there is a way in awk to test the next record before processing.

All I am trying to do is see if the next line equal something then turn a flag off.

Example:
Code:
Problem
Cron
IneedThis
KeyOnThis
somemoredata
somemoredata
Cron
somemoredata
somemoredata
IneedThis
KeyOnThis
somemoredata
somemoredata

From the above I am trying to turn a flag off when I see IneedThis followed by KeyOnThis

Is this possible with awk?

I tried using:
Code:
if ($1 == "Cron" ) {
f = " "
}

But Cron appears in multiple places in my file. Is there a way to look ahead with getline?
# 2  
Old 10-15-2009
Base on your sample data what is the required output.
# 3  
Old 10-15-2009
No output. I just need to change a variable to null and process the next line output.
# 4  
Old 10-15-2009
If we we know exactly what is to be done if true and what if not, then we can give better sugestion. SED also can do afew things, but not assign values. See ifthis is what u r looking 4.
Code:
old=''
while read new ; do
   if [ "$new" = "KeyOnThis" -a "$old" = "IneedThis" ] ; then
      myvar=""
   fi
   myvar="has a value"
   old=$new
done < myfile.txt
return 0

# 5  
Old 10-15-2009
Quote:
Originally Posted by timj123
From the above I am trying to turn a flag off when I see IneedThis followed by KeyOnThis

Is this possible with awk?
Something like that ?
Code:
awk '/IneedThis/{getline;flag=(/KeyOnThis/)?1:0}flag' file

# 6  
Old 10-16-2009
Thanks for the reply's. I will try both when I get a chance.
# 7  
Old 10-17-2009
Do you need to read ahead? Can't you do something like this?

Code:
nawk '
        /IneedThis/{ i = NR }
        /KeyOnThis/ && ( i == NR -1 ){ ++matched }
        { print }
        (matched){
                matched-- 
                printf("%s\n", "f  = \" \"") 
        }       
' infile

OP: -

Code:
Problem
Cron
IneedThis
KeyOnThis
f  = " "
somemoredata
somemoredata
Cron
somemoredata
somemoredata
IneedThis
KeyOnThis
f  = " "
somemoredata
somemoredata


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