重击减法 [英] Bash set subtraction

问题描述

如何在Bash中从另一个集合中减去一个集合?

How to subtract a set from another in Bash?

这类似于: 是bash中的数据结构吗?却有所不同，因为它询问如何使用代码进行减法

This is similar to: Is there a "set" data structure in bash? but different as it asks how to perform the subtraction, with code

• set1:N行由过滤器输出
• set2:由过滤器输出的M行

获取方式:

• set3:N中所有不出现在M中的行

推荐答案

comm -23 <(command_which_generate_N|sort) <(command_which_generate_M|sort)

不带选项的通讯显示3列输出:1:仅在第一个文件中； 2:仅在第二个文件中； 3:在两个文件中. -23删除第二和第三列.

comm without option display 3 columns of output: 1: only in first file, 2: only in second file, 3: in both files. -23 removes the second and third columns.

$ cat > file1.list
A
B
C
$ cat > file2.list
A
C
D
$ comm file1.list file2.list 
        A
B
        C
    D
$ comm -12 file1.list file2.list # In both
A
C
$ comm -23 file1.list file2.list # Only in set 1
B
$ comm -13 file1.list file2.list # Only in set 2
D

输入文件必须排序.

GNU排序和通讯取决于语言环境，例如输出顺序可能不同(但内容必须相同)

GNU sort and comm depends on locale, for example output order may be different (but content must be the same)

(export LC_ALL=C; comm -23 <(command_which_generate_N|sort) <(command_which_generate_M|sort))

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