Using awk to process input from multiple files

problem ：

Many people have been very helpful by posting the following solution for AWK'ing multiple input files at once: By publishing the following for AWK A solution for importing multiple input files at once , Many people are very helpful ：

$ awk 'FNR==NR{a[$1]=$2 FS $3;next}{ print $0, a[$1]}' file2 file1

This works well, but I was wondering if I someone could explain to me why? It's easy to use , But I wonder if anyone can explain to me why ？I find the AWK syntax a little bit tough to get the hang of and was hoping someone wouldn't mind breaking the code snippet down for me. I find AWK The grammar is a bit difficult to understand , And hope someone doesn't mind breaking up code snippets for me .

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Solution ：

Reference resources ： https://stackoom.com/en/question/10s6u