如何将转义码转换为 html 或删除

Question

Debian 中 ASP.NET 5 Core MVC 应用程序中的 Kestrel 将转义码写入 /var/log/syslog 文本文件，如

Apr  5 22:02:21 ew kestrel-store[31907]: #033[40m#033[32minfo#033[39m#033[22m#033[49m: Microsoft.Hosting.Lifetime[0]
Apr  5 22:02:21 ew kestrel-store[31907]:       Now listening on: http://localhost:5000
Apr  5 22:02:21 ew kestrel-store[31907]: #033[40m#033[32minfo#033[39m#033[22m#033[49m: Microsoft.Hosting.Lifetime[0]
Apr  5 22:02:21 ew kestrel-store[31907]:       Application started. Press Ctrl+C to shut down.
Apr  5 22:02:21 ew kestrel-store[31907]: #033[40m#033[32minfo#033[39m#033[22m#033[49m: Microsoft.Hosting.Lifetime[0]
Apr  5 22:02:21 ew kestrel-store[31907]:       Hosting environment: Production
Apr  5 22:02:21 ew kestrel-store[31907]: #033[40m#033[32minfo#033[39m#033[22m#033[49m: Microsoft.Hosting.Lifetime[0]
Apr  5 22:02:21 ew kestrel-store[31907]:       Content root path: /var/www/store5

这个文件被 MVC 控制器读取并发送给视图中的用户。

如何将此文件转换为 html（例如，使用彩色或斜体线）或从文件中删除转义码以使文件更易于阅读？ 或者如何强制红隼输出没有转义码的纯文本？

控制器代码：

public IActionResult Syslog()
{
    return new ContentResult()
    {
        Content = FileToStr("/var/log/syslog")
    };
}

static string FileToStr(string cFileName)
{
    StreamReader oReader = File.OpenText(cFileName);
    string lcString = oReader.ReadToEnd();
    oReader.Close();
    return lcString;
}

转义序列定义为：

1. 一个\x1b
2. 一个[
3. 零个或多个参数字节 0x30-0x3f
4. 零个或多个中间字节 0x20-0x2f
5. 最后一个字节 0x40-0x7f

更新

答案中的代码将跨度添加到每行的开头，并且不删除转义序列：

<span style="color: blue">Apr  8 00:00:05 ew rsyslogd:  [origin software="rsyslogd" swVersion="8.1901.0" x-pid="573" x-info="https://www.rsyslog.com"] rsyslogd was HUPed</span>
<span style="color: blue">Apr  8 00:00:05 ew systemd[1]: logrotate.service: Succeeded.</span>
<span style="color: blue">Apr  8 00:00:05 ew systemd[1]: Started Rotate log files.</span>
<span style="color: blue">Apr  8 00:00:10 ew colord[1172]: failed to get session [pid 23699]: No data available</span>
<span style="color: blue">Apr  8 00:00:12 ew colord[1172]: failed to get session [pid 23699]: No data available</span>
<span style="color: blue">Apr  8 00:00:14 ew colord[1172]: failed to get session [pid 23699]: No data available</span>
<span style="color: blue">Apr  8 00:05:01 ew CRON[23838]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)</span>
<span style="color: blue">Apr  8 00:15:01 ew CRON[24082]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)</span>
<span style="color: blue">Apr  8 00:17:01 ew CRON[24128]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)</span>
<span style="color: blue">Apr  8 00:21:49 ew kestrel-store[22413]: #033[40m#033[32minfo#033[39m#033[22m#033[49m: WebOptimizer.AssetMiddleware[1000]</span>
<span style="color: blue">Apr  8 00:21:49 ew kestrel-store[22413]:       Request started for '/c/version.js'</span>
<span style="color: blue">Apr  8 00:21:49 ew kestrel-store[22413]: #033[41m#033[30mfail#033[39m#033[22m#033[49m: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[1]</span>
<span style="color: blue">Apr  8 00:21:49 ew kestrel-store[22413]:       An unhandled exception has occurred while executing the request.</span>

预期输出是：

Answer 1

希望这会有所帮助。我用rextester.com写了一个格式化代码。但是文件测试在那里不起作用。

如有必要，请更正此帖子。它也不是最短的版本，但我认为它最清晰。

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Microsoft (R) Visual C# Compiler version 2.9.0.63208 (958f2354)

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            using (var reader = new StreamReader(@"c:\your_input_file.txt"))
            using (var writer = new StreamWriter(@"c:\your_output_file.html"))
            {
                WriteHtmlHeader(writer);
                string line;
                while((line = reader.ReadLine()) != null)
                {
                    line = AddSpan(line);
                }
                WriteHtmlFooter(writer);
            }
        }
        
        private static void WriteHtmlHeader(StreamWriter outfile)
        {
            // writing all the header and the start of body...
            // you can take it from another file
        }
        
        private static void WriteHtmlFooter(StreamWriter outfile)
        {
            // writing the footer of your html file
        }
        
        private static string AddSpan(string line)
        {
            if (Regex.IsMatch(line, "\x1b"))
            {
                return AddStyledSpan(line, "color: green");
            }
            else if (Regex.IsMatch(line, "\["))
            {
                return AddStyledSpan(line, "color: blue");
            }
            // ...
            else
            {
                // Mark this span as error or standard
                return AddStyledSpan(line, "color: red");
            }
        }
            
        private static string AddStyledSpan(string line, string style)
        {
            return "<span style=\"" + style + "\">" + line + "</span>";
        }
    }
}

希望这会有所帮助。也看看 regex101 - online regex tester 和 debuggex - regex visualization。 （但请谨慎使用，正则表达式的工作方式有时会有所不同）。