grep1

Simple node.js wrapper around the command-line utility grep

npm install grep1
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Grep

This is a simple wrapper around grep(1). The module use child_process to create grep processes and use streams and callbacks to communicate.

Install

Using npm:

$ npm install grep1

From source:

$ git clone https://github.com/ladinu/node-grep.git
$ cd node-grep
$ npm link

Examples

Grep file /tmp/file for expression spurs:

var grep = require('grep1');

grep(['spurs', '/tmp/file'], function(err, stdout, stderr) {
  if (err || stderr) {
    console.log(err, stderr);
  } else {
    console.log(stdout);
  }
});

Grep file /tmp/file for expression spurs:

var search = grep(['spurs', '/tmp/file']);

search.pipe(process.stdout);

search.on('error', function(err) {
  console.log(err);
});

Using request, grep example.com for expression examples

var req    = require('request');
var search = grep('examples');

search.pipe(process.stdout);
req('http://example.com').pipe(search);

API

Class: Grep

This class wrap grep(1) using node's child_process module. When a callback is given child_process.execFile() is used and returns a Grep object which is a destroyed stream. When no callback, child_process.spawn() is used and returns a Grep object which is a stream.

Event: 'error'

Process's stderr is emitted as error events.

Event: 'data'

Process's stdout is emitted as data events.

grep([args], [options], callback)

  • args The arguments given to grep(1) processes. By default args is concatinated with an empty array and passed to grep(1) process. See options to change this behaviour.

  • options Object for Grep object. Note

    • buildArgs Function that build arguments for grep(1) processes. By default this is set to a function that concatinate given args to an empty array. So when you call grep("some_phrase") the actual arguments given to grep(1) process is [ 'some_phrase' ].

    • execOptions Object that give options such as cwd to each grep(1) process. By default this is an empty object. This is the same options object that you would use when calling child_process.execFile() or child_process.spawn(). Because a callback is given, child_process.execFile() is used. See node documentation for more information.

  • callback Function that is called when grep(1) process terminate

    • error Error
    • stdout Buffer
    • stderr Buffer
  • Returns a Grep object

grep([args], [options])

  • args Same as grep([args], [options], callback)

  • options Same as grep([args], [options], callback) except child_process.spawn() is used. See node documentation for more infromation

  • Returns a Grep object

grep.configure([options])

This will make options global when options is not given to grep([args], [options]) or grep([args], [options], callback)

  • Returns: nothing

For example:

var grep = require('grep1');

// Set buildArgs so grep(1) will count line numbers.
// Set current working directory to '/var/log' and perform
// grep operations on file 'some.log'
//
// When you call grep("phrase"), a new grep(1) process will
// be created with arguments ['-n', 'phrase', 'some.log']

var fs      = require('fs');
warningFile = fs.createWriteStream('./warnings.txt');
errorFile   = fs.createWriteStream('./errors.txt');

grep.configure({
    buildArgs:    function(args) { return ['-n', args, 'some.log'] }
  , execOptions:  {cwd: '/var/log'}
});

var warning = grep('[+} Warning');
var errors  = grep('[!] Error');

warning.pipe(warningFile);
errors.pipe(errorFile);


// Grep file '/tmp/foo.txt' for first occurance of 'bar'
// Note: global options set above do not apply because we 
// are giving an an empty options object

var options = {};
var bar     = grep(['-m', '1', 'bar', '/tmp/foo.txt'], options);
bar.pipe(process.stdout);

grep.resetConfig()

Helper method to clear global settings. This basically set buildArgs to null and execOptions to an empty object.

License

Copyright (c) 2013 Ladinu Chandrasinghe

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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