How to get matched string from file using file System and nodejs?

Question

I am passing string from client side and if that string is part of that file content i want to print that line , is it doable using fs and nodejs ?

searvice.js

var fs = require('fs');
var path = require('path');
var async = require('async');
var searchStr;

function readFile(str){
    searchStr = str;
//  var url = './logs/St/server1.log';
    fs.readFile('./logs/St/server1.log', 'utf8', function (err,data) {
      if (err) {
        return console.log(err);
      }
      console.log('Server Data',data);
      inspectFile(data);
    });
}


function inspectFile(data) {
    if (data.indexOf(searchStr) != -1) {
        // do something
        console.log('print the matching data');
    }
}

exports.readFile = readFile;

Do you want to print all the lines that matched or just the first one? — ibrahim mahrir
– ibrahim mahrir, Commented Feb 24, 2017 at 20:09

ibrahim mahrir · Accepted Answer · 2017-02-24 20:12:33Z

1

You have first to split data by new lines. Try this:

function inspectFile(data) {
    var lines = data.split('\n');              // get the lines
    lines.forEach(function(line) {             // for each line in lines
        if(line.indexOf(searchStr) != -1) {    // if the line contain the searchStr
            console.log(line);                 // then log it
        }
    });
}

Note: instead of making searchStr global, you could just pass it as parametter to inspectFile.

answered Feb 24, 2017 at 20:12

ibrahim mahrir

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4 Comments

hussain Over a year ago

How you see this approach in case of async it will work ?

ibrahim mahrir Over a year ago

@hussain you're calling it from inside the callback of the asynch function so I think it'll work.

ibrahim mahrir Over a year ago

@hussain Did you try it?

hussain Over a year ago

Yeah it worked what i was trying to achieve. Thanks alot

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