sed，替换第一行的第一个匹配项

Question

我的文字如下

this This that
it It Its
my My Mine
this This that
it It Its
my My Mine

我想替换第一个匹配项的第一行。 例如。 匹配包含my的行，然后替换行。 我做了

cat txt|sed "0,/my/c\my changed line" txt

打印内容如下所示，前两行被剪裁。

my changed line
this This that
it It Its
my My Mine

如果我运行cat txt|sed "s/my/changeline/" txt

输出如下

this This that
it It Its
changeline My Mine
this This that
it It Its
changeline My Mine

如何获得如下所示的结果？

this This that
it It Its
changeline My Mine
this This that
it It Its
my My Mine

Answer 1

使用sed ：

sed '0,/.*my.*/s//my changed line/' file

这样做是在0,/.*my.*/范围内，它将匹配的.*my.*替换为“我的更改的行”。

相同的东西的同等版本稍微容易理解：

sed '0,/my/{/.*my.*/s//my changed line/}' file

使用awk的逻辑稍微容易理解：

awk '!/my/ || seen { print } /my/ && !seen { print "my changed line"; seen = 1 }' file

Answer 2

$ awk '/my/ && !f++{$0="changeline My Mine"} 1' file
this This that
it It Its
changeline My Mine
this This that
it It Its
my My Mine