How to use the current line as a parameter to execute a shell command in vim?

Question

1 hello
2 world
3 me

For example, I am currently on the second line, how do I execute !echo world?

Answer 1

:.w !command命令可以把当前行送到命令的标准输入，比如:.w !cat，当然这不满足你的需求，因为你要的是作为命令行参数，所以你可以这么用：
:.w !xargs command
Okay I know it looks ugly, but it works...

Answer 2

:echo getline('.')