node.js log errors in file

Question

I'm trying to log errors to a file in node.js. i tried winston:

winston= require('winston');
var logger = new (winston.Logger)({
transports: [
new (winston.transports.Console)({ level: 'error' }),
new (winston.transports.File)({ filename: 'error.log' })
]
});

I also tried console.error:

var log_file_err=
fs.createWriteStream(__dirname + '/error.log', {flags : 'a'});

var err_stdout = process.stderr;

console.error = function(d) { //
log_file_err.write(util.format(d) + '\n');
err_stdout.write(util.format(d) + '\n');
};

to generate an error i used:

function get_time(date)
{
     return date.getHours()+':'+date.getMinutes();
}
console.log(get_time(Date()));//instead of new Date()

i get no further errors(just the wanted undefined for Date()) but error.log stays empty."debug.log"(normal logging)where i use an overidden console.log works correctly.

no ideas? is this kind of error not written in the file because the app is crashing? if this the reason,how can i then log such errors to a file? — user3776738
– user3776738, Commented Feb 15, 2015 at 12:37
In your winston error log definition, if you pass in level: 'error' that will log fatal errors. I'm not sure how to capture all console.errors (still trying to figure that out) — ccnokes
– ccnokes, Commented Feb 25, 2015 at 17:40

user3776738 · Accepted Answer · 2015-03-26 11:02:17Z

5

Finally i found a solution which works perfectly for me:

var log_file_err=fs.createWriteStream(__dirname + '/error.log',{flags:'a'});  

process.on('uncaughtException', function(err) {
console.log('Caught exception: ' + err);
log_file_err.write(util.format('Caught exception: '+err) + '\n');
});

answered Mar 26, 2015 at 11:02

user3776738

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1 Comment

rgbflawed Over a year ago

This works okay for me. Doesn't give me the most details about what went wrong but at least it's something. Note that for this to work you need to define: const fs = require('fs'); and const util = require('util');

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