linux - 比较两个文件并合并数据

Question

我有以下文件，

total.txt

order1,5,item1
order2,6,item2
order3,7,item3
order4,6,item4
order8,9,item8

已更改.txt

order3,8,item3
order8,12,item8

total.txt为总订单数据，changed.txt为最近变动数据。我想将最近的更改与总计合并，我希望输出为，

输出.txt

order1,5,item1
order2,6,item2
order3,8,item3
order4,6,item4
order8,12,item8

注意:total.txt 的第 2 列(第 3 和第 5)行已使用已更改的 .txt 文件更新

我已经使用下面的nawk 来比较第一个coulmn，但无法将它打印到输出文件。请帮助完成以下命令

nawk -F","'NR==FNR {a[$1]=$2;next} ($1 in a) "print??"' total.txt changed.txt

Answer 1

另一个awk

awk -F, 'FNR==NR {a[$1]=$0;next} {print (a[$1]?a[$1]:$0)}' changed.txt total.txt
order1,5,item1
order2,6,item2
order3,8,item3
order4,6,item4
order8,12,item8

---

它是如何工作的？

awk -F, '                       # set field separator to ","
    FNR==NR {                   # run this only on first file "changed.txt"
        a[$1]=$0                # store "changed.txt" in array "a" using first field as index
        next                    # skip to next record
    }
        {                       # run this when second file is read "total.txt"
        print (a[$1]?a[$1]:$0)  # if filed exist in "changed" use that, else use "total"
    }' changed.txt total.txt    # read these files