如何使用awk替换第二个实例一次

Question

下面的脚本似乎替换了第二个实例。-我可以如何调整awk命令，使它只替换第二个实例一次？

脚本位置引用一个名为basicTest.jmx的文件，该文件包含以下txt

hashTree
hashTree
hashTree
hashTree
hashTree
hashTree
hashTree

下面是剧本：

scriptLocation="basicTest.jmx"

myVar="FOOO__BARRRR"

awkOut=$(awk -v s='hashTree' -v myVar="$myVar" '$0~s{c++} c==2{sub(s, myVar); c=0} 1' "${scriptLocation}")  
echo "$awkOut" > $scriptLocation

这就是我需要输出的样子：

hashTree
FOOO__BARRRR
hashTree
hashTree
hashTree
hashTree
hashTree

这是当前错误的输出：

hashTree
FOOO__BARRRR
hashTree
FOOO__BARRRR
hashTree
FOOO__BARRRR
hashTree

Answer 1

删除c=0修复了问题:下面的工作版本。-谢谢大家的帮助。

awkOut=$(awk -v s='hashTree' -v myVar="$myVar" '$0~s{c++} c==2{sub(s, myVar); } 1' "${scriptLocation}")  

Answer 2

$ awk -va=hashTree -vb=FOOO__BARRRR '$1~a&&++c==2{$1=b}1' filename
hashTree
FOOO__BARRRR
hashTree
hashTree
hashTree
hashTree
hashTree