awk getline


 
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# 1  
Old 06-01-2009
awk getline

How do you make the getline function return to the original line?
The example below should make it clear where I am currently going wrong.

Thanks

AWK SCRIPT:
-------------
awk -F '-' '{
tmpLine = "EMPTY"
print "CURRENT LINE :"$0
getline tmpLine
print "NEXT LINE :"tmpLine
}' testawk.txt

testawk.txt
--------------
1-TEST-FILE-NEW
2-TEST-FILE-NEW
3-TEST-FILE-NEW
4-TEST-FILE-NEW
5-TEST-FILE-NEW
6-TEST-FILE-NEW
7-TEST-FILE-NEW

output:
-------
CURRENT LINE :1-TEST-FILE-NEW
NEXT LINE :2-TEST-FILE-NEW
CURRENT LINE :3-TEST-FILE-NEW
NEXT LINE :4-TEST-FILE-NEW
CURRENT LINE :5-TEST-FILE-NEW
NEXT LINE :6-TEST-FILE-NEW
CURRENT LINE :7-TEST-FILE-NEW
NEXT LINE : EMPTY

desired output
--------------
CURRENT LINE :1-TEST-FILE-NEW
NEXT LINE :2-TEST-FILE-NEW
CURRENT LINE :2-TEST-FILE-NEW
NEXT LINE :3-TEST-FILE-NEW
CURRENT LINE :3-TEST-FILE-NEW
NEXT LINE :4-TEST-FILE-NEW
CURRENT LINE :4-TEST-FILE-NEW
NEXT LINE :5-TEST-FILE-NEW
CURRENT LINE :5-TEST-FILE-NEW
NEXT LINE :6-TEST-FILE-NEW
CURRENT LINE :6-TEST-FILE-NEW
NEXT LINE :7-TEST-FILE-NEW
CURRENT LINE :7-TEST-FILE-NEW
NEXT LINE : EMPTY
# 2  
Old 06-01-2009
So what you're trying to do is read ahead by one line without affecting the input? Not possible. You need to write some code that will keep two lines in a buffer and process those instead, perhaps a bit like this:

Code:
awk '{ d[(i=(i+1)%2)]=$0; out(); j=(j+1)%2 }
     END { d[(j+1)%2]="EMPTY"; out() }
     function out() {
        if (d[j]) print "CURRENT LINE: " d[j] "\nNEXT LINE: " d[(j+1)%2]
     }' testawk.txt

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