system2 调用软连接程序怎么在文件存在时报错退出

Liripo

比如，一个R脚本，test.R

file.create("a.txt")
dir.create("test")
system2("ln",args = c("-s","a.txt","./test"),stderr = T)
system2("ln",args = c("-s","a.txt","./test"),stderr = T)

当我运行Rscript test.R时，退出状态码是0。
应该怎么让这个脚本在第二次调用system2("ln",args = c("-s","a.txt","./test"),stderr = T)时候报错停止呢

InfinityLoop

Liripo

file.create("a.txt")
dir.create("test")
status <- system2("ln",args = c("-s","a.txt","./test"),stderr = T)

if (length(status) == 0) {
  stop('报错，退出脚本')
} else {
  system2("ln",args = c("-s","a.txt","./test"),stderr = T)
}

Liripo

InfinityLoop 谢谢