Shell Programming and Scripting

Yes, that is correct. Awk uses so-called associative arrays..

understood, thanks.

speaking of making the code for efficient, the current method will become expensive soon as file 2 will grow to thousands of lines whereas file1 will only be around 20-30 lines at most. so currently, the code will iterate through each line of file2 and compare against file1 (which is loaded in the array).

it would be more economical to switch this around i.e load file2 into the array and lookup file1 so if file1 only has 5 lines, it will stop at that and hence be quicker. is my logic correct?

found my first little "bug" with this, more like "shortcoming" as i didnt plan for it.
if file one has field1 appearing more than once (on a separate line), i would need that in the output with its corresponding field2. eg:

cat file1

Code:

foo,cmd1
bar,cmd2
foo,cmd3

cat file2

Code:

Hello,World,foo
Alice,Bob,bar
Egg,Spam,ham

desired output:

Code:

World,fi,fom,cmd1
Bob,bie,doll,cmd2
World,fi,fom,cmd3

currently this is not the case as the script looks in file2 and if field3 is found in array A, prints the output. this will only ever match once as field3 will only be in file2 once. hope that makes sense.

i think we need to do a reverse look up perhaps? i.e use field1,file1 and lookup against file2?