如何对使用RunLoop的macOS控制台应用程序的标准输出进行grep

let outputFilePath = "/path/to/output.txt"
freopen(outputFilePath, "a+", stdout)

let fileURL = URL(fileURLWithPath: outputFilePath)
let outputString = try String(contentsOf: fileURL)

let pattern = "your_grep_pattern"
let regex = try NSRegularExpression(pattern: pattern)
let matches = regex.matches(in: outputString, range: NSRange(outputString.startIndex..., in: outputString))

for match in matches {
    let matchRange = match.range
    let matchedString = outputString[Range(matchRange, in: outputString)!]
    print(matchedString)
}