linux - sed，替换第一行的第一次匹配

Question

我的文字如下所示

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

我想替换第一次匹配的第一行。例如。匹配包含 my 的行，然后替换该行。我做了

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

下面是打印出来的，前两行被剪掉了。

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

如果我运行这个 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

我怎样才能得到像下面这样的结果？

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

这是做什么的，在 0,/.*my.*/ 范围内，它将用“我更改的行”替换匹配的 .*my.*。

同一事物的等效版本:

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

使用 awk 逻辑更容易理解:

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