awk getline

Shell Programming and Scripting
1

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

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:

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