grep1

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

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Readme

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

Examples

Grep file /tmp/file for expression spurs: 
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 request2, grep example.com1 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_pharse")` 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][4] 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][3] 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: 
// 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.