Rails Benchmark Execution Time

Sometimes we need to benchmark the execution time of a code segment to check the performance.
For this we can use the `Benchmark` library available in Rails like below.

puts '====== Start benchmark ========'
time = Benchmark.realtime {
  ... Code being tested goes here ... 
}
puts time
puts '====== End benchmark =========='

Disable Ember CLI Mirage in a specific test

There can be a scenario where you want to disable ember-cli-mirage server in a specific test file; acceptance specially. You can do that by shutting down the Mirage server in `beforeEach()` in an acceptance test. For example,

```
moduleForAcceptance('Acceptance | test name', {
  beforeEach() {
    server.shutdown();
  }
});
```

Run Ember Tests without running `ember t -s`

It is possible to run the Ember server with `ember s` on one port 4200 by default and testing with `ember t -s` on port 7357 by default.

However, it is possible to run the server and run the tests on that same port (4200) as well just by navigating to `http://localhost:4200/tests` after running `ember s`

Merge pdf files into one pdf file using GhostScript on Linux

Command:

gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=finished.pdf file1.pdf file2.pdf

Explanation:

• gs starts the Ghostscript program. 
• -dBATCH once Ghostscript processes the PDF files, it should exit. If you don't include this option, Ghostscript will just keep running. 
• -dNOPAUSE forces Ghostscript to process each page without pausing for user interaction. 
• -q stops Ghostscript from displaying messages while it works 
• -sDEVICE=pdfwrite tells Ghostscript to use its built-in PDF writer to process the files. 
• -sOutputFile=finished.pdf tells Ghostscript to save the combined PDF file with the specified name.

Crop a video file using ffmpeg

If you want to crop the file beyond 1 min then use the -t flag and as follows. It will generates the output.avi video with the first 60 seconds of the input.avi

ffmpeg -t 60 -i input.avi -an -vcodec copy output.avi

CSS clearfix

.group:before,
.group:after {
  content: "";
  display: table;
}

.group:after {
  clear: both;
}

.group {
  zoom: 1 /* IE6&7 */
}

Make Odin flashable tar.md5 on Linux

Steps:

1. tar -H ustar -c image_1 image_2 > your_odin_package.tar
2. md5sum -t your_odin_package.tar >> your_odin_package.tar
3. mv your_odin_package.tar your_odin_package.tar.md5

You are done!!!

Enjoy!