Question

我正在从文件appliance_list.txt中读取一个字符串。

appliances_list.txt包含

fridge
dryer
ironbox
microwave

我正在阅读的文件是myappliances.txt。内容是

I have a fridge
I have another fridge
I have a refridgerator
I have a microwave
I have ironbox at home
I have another microwave
I have a hairdryer

我正在使用

grep -o -m1 -f appliances_list.txt myappliances.txt

输出

fridge

我想要的输出是，第一次出现每个字符串（完全匹配）

fridge
microwave
ironbox

有人能指出我正确的方向吗？

Answer 1

一个使用awk：

$ awk 'NR==FNR{a[$1]=1;next}a[$2]==1{print $2;a[$2]++}' pattern sample
Pattern1
Pattern2
Pattern3

说明：

$ awk '           # well, awk
NR==FNR {         # for the first file
    a[$1]=1       # hash each keyword and set it as 1
    next          # next record
}
a[$2]==1 {        # second file, if the word in 2nd column was hashed and 1
    print $2      # output it
    a[$2]++       # and increase its value above 1
}' pattern sample # mind the order

从文件中读取模式，grep只发生第一次

1 个答案: