a在文件中搜索字符串并打印第二列 [英] Lua. Search string in a file and print second column

问题描述

在Lua中寻找替换以下命令的解决方案:

Looking for solution to replace following command in Lua:

grep "dhcp-range" /tmp/etc/dnsmasq.conf | awk -F "\"*,\"*" '{print $2}'

尝试

for line in file:lines() do
        if line:match("([^;]*),([^;]*),([^;]*),([^;]*),([^;]*)") then
                print(line[2])
        end
end

它不起作用.

/tmp/etc/dnsmasq.conf看起来像这样

/tmp/etc/dnsmasq.conf looks like this

dhcp-leasefile=/tmp/dhcp.leases
resolv-file=/tmp/resolv.conf.auto
addn-hosts=/tmp/hosts
conf-dir=/tmp/dnsmasq.d
stop-dns-rebind
rebind-localhost-ok
dhcp-broadcast=tag:needs-broadcast

dhcp-range=lan,192.168.34.165,192.168.34.179,255.255.255.0,12h
no-dhcp-interface=eth0

推荐答案

在Lua中，这是一个函数，如果将整个文件内容传递给它，它将打印所需的值:

Here is a function in Lua that will print the values you need if you pass the whole file contents to it:

function getmatches(text)
    for line in string.gmatch(text, "[^\r\n]+") do
        m,n = string.match(line,"^dhcp%-range[^,]*,([^,]+),([^,]+)")
        if m ~= nil then 
            print(m,n) 
        end
    end
end

请参见 Lua演示

使用 string.gmatch(text，"[^ \ r \ n] +")，访问每个文件行(根据需要调整)，然后主要部分是m,n = string.match(line,"^dhcp%-range[^,]*,([^,]+),([^,]+)") 实例化 m(第一个IP)和 n (第二个IP)在以 dhcp-range 开头的行中找到.

With string.gmatch(text, "[^\r\n]+"), each file line is accessed (adjust as you see fit), and then the main part is m,n = string.match(line,"^dhcp%-range[^,]*,([^,]+),([^,]+)") that instantiates m with the first IP and n with the second IP found on a line that starts with dhcp-range.

Lua模式详细信息:

• ^ -字符串的开头
• dhcp％-range -文字字符串 dhcp-range (-是Lua中的匹配0个或多个匹配项的量词，但是
越少越好，并且要匹配文字-，必须对其进行转义.正则表达式转义由％组成.
• [^，] *，-0 +个除，以外的字符，然后是，
• ([[^，] +)-组1( m ):除，
以外的一个或多个字符
• ，-逗号
• ([[^，] +)-组1( n ):除，以外的一个或多个字符.

• ^ - start of string
• dhcp%-range - a literal string dhcp-range (a - is a quantifier in Lua matching 0 or more occurrences, but as few as possible, and to match a literal -, it must be escaped. Regex escapes are formed with %.)
• [^,]*, - 0+ chars other than , and then a ,
• ([^,]+) - Group 1 (m): one or more chars other than ,
• , - a comma
• ([^,]+) - Group 1 (n): one or more chars other than ,.

这篇关于a在文件中搜索字符串并打印第二列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！