$ jtxt 'var it = l.split("]")[2]; console.log(it)' gc.log

Quick Start

Download binary from release or install with cargo

从release页下载或者直接用cargo安装

$ cargo install jtxt

Usage

$ jtxt -h
Processes lines of input with JavaScript

Usage: jtxt [OPTIONS] <function> [file]

Arguments:
  <function>  JavaScript code to process each line, l is the origin string
  [file]      Path to the input file. If not provided, reads from stdin.

Options:
  -b, --begin <begin>  JavaScript code to execute before processing any lines
  -e, --end <end>      JavaScript code to execute after processing all lines
  -h, --help           Print help
  -V, --version        Print version

Example with 1.txt

# 1 filter the lines that only contains numbers from 1.txt
# 1 从1.txt中过滤全是数字的行
$ jtxt 'if (l.match(/^\d+$/)) console.log(l)' 1.txt
200
404
200

# 2 compute the character number of 1.txt (exclude the [\r]\n)
# 2 计算1.txt中的字符个数(除了换行符[\r]\n)
$ jtxt -b 'var s=0' 's += l.length' -e 'console.log(s)' 1.txt
144

# 3 filter the lines that contains `Request`, and process the time text, then analyze the distribution of quantity per hour
# 3 过滤含有Request的行，并将时间部分进行处理，分析每个小时的请求数量分布
$ jtxt 'if(l.indexOf("Request")>=0) console.log(l)' 1.txt \
    | jtxt -b 'var m={}' 'var k = "h" + new Date(l.substring(0,19)).getHours(); if(!m[k]) m[k]=0; m[k]++' -e 'console.log(m)' 1.txt
{
  "h13": 2,
  "h14": 1
}

Well, to simplify the command, you can also use the preset variable: var ctx = {}, n1=0, n2=0, n3=0, s='', arr=[];

你也可以用内置的变量来简化指令，这是几个内置变量和他们的默认值var ctx = {}, n1=0, n2=0, n3=0, s='', arr=[];

Performance

The performance is about 4 times slower in simple scenarios compared to awk, because of using deno_core to interpret code. For example, count the character. But in the other hand, you get the JavaScript support.

简单场景下，例如字符计数，性能比awk差了4倍，这是因为使用了deno_core来解释运行，但反过来讲，你获得了JavaScript语法的支持。

gc.log is a jvm gc log 32M size.

In complex scenarios, the performance gap will narrow, and even reverse. For example, compute the gc count and gc time in every second, and finally return the top 1 item (the longest).

复杂场景下，性能差距会缩小甚至反超。例如计算每秒的gc总数量和gc总时间，最终返回最长的那一秒

$ jtxt 'var re=l.match(/(\d{4}-\d\d-\d\dT\d\d:\d\d:\d\d).*Real=([0-9\.]+)/); 
  if (re) { 
    if (!ctx[re[1]]) ctx[re[1]] = 0; 
    ctx[re[1]]+=parseFloat(re[2]) 
  }' -e 'for (var k in ctx)  { 
    if (ctx[k]>n1) { n1 = ctx[k]; n2 = k} 
  } 
  console.log(`最大时间: ${n2}, 最大值: ${n1}`)' gc.log

$ awk '{ if (match($0, /([0-9]{4}-[0-9]{2}-[0-9]{2})T([0-9]{2}:[0-9]{2}:[0-9]{2}).*Real=([0-9\.]+)/, arr)) {
        time = arr[1] "T" arr[2];
        value = arr[3];
        sum[time] += value;}
} END {
    max_value = 0;
    max_time = ""; 
    for (t in sum) {
        if (sum[t] > max_value) {
            max_value = sum[t];
            max_time = t; 
        }
    }
    print "最大值时间: " max_time ", 最大值: " max_value;
}' gc.log