bash Unix 代码想要更改列值
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Unix code wanted to change column values
提问by Abdel
I have a file that looks like this:
我有一个看起来像这样的文件：
ID1 ID2 3
ID2 ID3 3
ID4 ID5 3
ID6 ID7 4
ID8 ID9 4
ID8 ID6 4
And I want to change it to:
我想把它改成：
ID1 ID2 1
ID2 ID3 1
ID4 ID5 1
ID6 ID7 2
ID8 ID9 2
ID8 ID6 2
So I want to change all 3's and 4's from the third column to 1's and 2's respectively. What is the most efficient way to do this for a very large file? Many thanks in advance!
所以我想将第三列中的所有 3 和 4 分别更改为 1 和 2。对于非常大的文件，执行此操作的最有效方法是什么？提前谢谢了！
回答by Mark Reed
awk '{ -= 2; print }' filename >new_filename
Or, if you really only want to touch 3's and 4's:
或者，如果您真的只想触摸 3 和 4：
awk '{ if ( == 3 ) { = 1 } else if ( == 4 ) { = 2 }; print}' filename >new_filename
回答by aland
Assuming third column is always the last one:
假设第三列总是最后一列：
sed 's/\([^0-9]\)3$//;s/\([^0-9]\)4$//'
