使用 Bash 从文件中提取不同的行

Question

我有两个文件，我使用“comm -23 file1 file2”命令来提取与另一个文件不同的行。

我还需要提取不同行但还保留字符串“line_$NR”的东西。 例子： 文件1：

line_1: This is line0
line_2: This is line1
line_3: This is line2
line_4: This is line3

文件2：

line_1: This is line1
line_2: This is line2
line_3: This is line3

我需要这个输出： 差异文件1文件2：

line_1: This is line0.

总之，我需要提取差异，就好像文件在开始时没有 line_$NR 但是当我打印结果时我还需要打印 line_$NR。

Answer 1

尝试使用awk

awk -F: 'NR==FNR {a[$2]; next} !($2 in a)' file2 file1

输出：

line_1: This is line0

简短说明

awk -F: '             # Set filed separator as ':'. $1 contains line_<n> and $2 contains 'This is line_<m>'
    NR==FNR {         # If Number of records equal to relative number of records, i.e. first file is being parsed
        a[$2];        # store $2 as a key in associative array 'a'
        next          # Don't process further. Go to next record.
    } 
    !($2 in a)        # Print a line if $2 of that line is not a key of array 'a'
' file2 file1

---

附加要求（评论中）

如果我在一行中有多个“：”：“line_1：这个：is：line0” 不起作用。怎么才能只走line_x

在这种情况下，请尝试以下操作（仅限GNU awk）

awk -F'line_[0-9]+:' 'NR==FNR {a[$2]; next} !($2 in a)' file2 file1

Answer 2

这条 awk 行更长，但是无论差异位于何处，它都可以工作：

awk 'NR==FNR{a[$NF]=$0;next}a[$NF]{a[$NF]=0;next}7;END{for(x in a)if(a[x])print a[x]}' file1 file2

测试：

kent$  head f*
==> f1 <==
line_1: This is line0
line_2: This is line1
line_3: This is line2
line_4: This is line3

==> f2 <==
line_1: This is line1
line_2: This is line2
line_3: This is line3

#test f1 f2
kent$  awk 'NR==FNR{a[$NF]=$0;next}a[$NF]{a[$NF]=0;next}7;END{for(x in a)if(a[x])print a[x]}' f1 f2
line_1: This is line0

#test f2 f1:    
kent$  awk 'NR==FNR{a[$NF]=$0;next}a[$NF]{a[$NF]=0;next}7;END{for(x in a)if(a[x])print a[x]}' f2 f1
line_1: This is line0