CODEWITHSUNDEEP
javascriptnode.jsbashfilegrep
dkx22
dkx22

Reputation: 1133

Different result when I use grep with node child_process than in bash

I'm trying to recursively grep for ip addresses in a directory. I have two files, one and two:

└┼─$─┤▶ cat one 
test
192.168.1.2
192.168.1.1102
182982
19829872.28288222.222982
sqdqssdsqd:12.92822.sldql
192.168.1.91

└┼─$─┤▶ cat two 
edezdzedezdezdezd:&&122.12
&&é&

ddzez
efreffe
np.ip

Here's how I use grep to get ip's:

└┼─$─┤▶ grep -sRIEoh '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
192.168.1.2
192.168.1.110
192.168.1.91
192.99.99.99

And I'm tring to do the same in node using child_process:

var spawn = require('child_process').spawn
var child


function puts(error, stdout, stderr) { console.log(stdout,error,stderr); process.exit();  }
const grep =spawn('grep',['-sRIEoh' ,'[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}','/home/user/test'])
const uniq = spawn('uniq');


grep.stdout.pipe(uniq.stdin);
grep.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

But the result is different for some reason...

└┼─$─┤▶ node test.js 
stdout: 192.168.1.2
192.168.1.110
19829872.282
88222.222982
12.92822
192.168.1.91
192.99.99.99

Upvotes: 0

Views: 81

Answers (1)

Andreas Louv
Andreas Louv

Reputation: 47099

Backslashes is used as a escape character in JavaScript, almost like it's in double quotes in Bash, the main exception is that JavaScript will remove the backslash if it cannot be used in a escape, consider the following:

% echo "\y"
\y
% node -e "console.log('\y')"
y

This means that you will need to escape backslashes that are used to escape . in grep:

 [0-9]{1,3}\.

should be:

 [0-9]{1,3}\\.

The full spawn line:

const grep = spawn('grep', ['-sRIEoh', 
    '[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}','/home/user/test']);

Upvotes: 1

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