Recently the question in the Readmill company chat came up on how what read to learn Ruby and Rails best. This is the links that were posted:

http://pragprog.com/book/rails4/agile-web-development-with-rails
http://railscasts.com/
http://rubykoans.com/
http://mislav.uniqpath.com/poignant-guide/
http://techiferous.com/2010/07/roadmap-for-learning-rails/
http://www.codecademy.com/
http://www.codeschool.com/
http://railsforzombies.org/

When developing you often come about a part in a gem you want to change. You will fork the gem and/or create a pull request later. But for testing, you often want to see how your change performs locally int he context of your project first.

So you locally clone the gem, start making your changes. To integrate, use this code:

$LOAD_PATH << 'local/path/to/gem/lib'
require 'gemname.rb'

For example in Rails you can put it in your `application.rb`. Also uncomment the orginal gem in your Gemfile. Once you are happy with your changes, push them to Github. To use the with bundler, put this in your Gemfile:

#gem 'gemname'
gem 'gemname', :git => 'git://github.com/user/gemname.git', :branch => 'your_branch'

Note: Your git repository has to be publicly accessible.

In GNU screen you can’t use the normal terminal scrolling. One way to still retrieve your history is by switching into copy mode via

C-a [ or  C-a ESC

You can then use the arrow or movement keys

h j k l

for scrolling. Exit with ESC. Yay.

Parts of my Rails code have a good portion of logging code, because I want to observe it’s behavior closely in the real world. I will probably remove the logging code, once I’m confident enough with the code

But during testing these log lines distract me from the test results and hide other stuff. So I decided it is better to disable it. I did this by adding the following code to /config/environments/test.rb

# disable logger
class EmptyLogger < StringIO
  def write(input)
    # do nothing
  end
end
config.logger = Logger.new(EmptyLogger.new)

This writes all log messages to a StringIO object, which does nothing with it …

When using curl to call REST APIs returning JSON, it is often hard to see the structure of the response. We need to prettify that! Fortunately, the Ruby json gem has a script called “prettify_json.rb”, that we can just pipe JSON to. Awesome.

Install the json gem

gem install json

Use it

$ curl "http://api.soundcloud.com/users/4126.json" | prettify_json.rb

{
  "id": 4126,
  "permalink": "diskodna",
  "username": "DiskoDNA",
  ...
  "website": "http://www.diskodna.de",
  "website_title": null,
  "online": false,
  "track_count": 11,
  "followers_count": 545,
  "followings_count": 311,
  "public_favorites_count": 93
}

When working remote via SSH, you often want to make sure that your processes continue to run, even if your connection dies. Screen is the tool for that. It creates shell sessions, that are detached from your terminal session. Thus they run, without you being connected. Also different users can share screen sessions with each other.

This are some of the basic commands:

Open a new screen session

screen

Get out of a running screen session (detach from terminal)

screen -d
C-a C-D

What screen sessions are already there?

screen -list

If there already is one, let’s open that (attach it to your current terminal session)

screen -r

Or specify the screen to open

screen -r [sessionowner]/[pid.tty.host]

Read more on the screen man page

man screen

caption always "%{kg}%?%-Lw%?%{bw}%n*%f %t%?(%u)%?%{kr}%?%+Lw%?"

> a = {}
 => {} 
> a['content-type'] = "My first string"
 => "My first string" 
> a['Content-Type'] = "My second string"
 => "My second string" 
> a
 => {"content-type"=>"My first string",
     "Content-Type"=>"My second string"} 

When using irb, the prompt might get cluttered bad, if you handle huge objects, since irb always returns the last object. To clean this up, just append ; nil to your input. This will return nil, since it is the last object.

Cluttered:

> numbers = (1..1000).collect { |i| i }
 => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76,
77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104,
105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116,
117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128,
129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,
141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152,
153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164,
165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176,
177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188,
189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200,
201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212,
213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224,
225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236,
237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248,
249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260,
261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272,
273, 274, 275, 276, 277, 278, 279, 280, 281, 282, 283, 284,
285, 286, 287, 288, 289, 290, 291, 292, 293, 294, 295, 296,
297, 298, 299, 300, 301, 302, 303, 304, 305, 306, 307, 308,
309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320,
321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332,
333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344,
345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356,
357, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368,
369, 370, 371, 372, 373, 374, 375, 376, 377, 378, 379, 380,
381, 382, 383, 384, 385, 386, 387, 388, 389, 390, 391, 392,
393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404,
405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416,
417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428,
429, 430, 431, 432, 433, 434, 435, 436, 437, 438, 439, 440,
441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452,
453, 454, 455, 456, 457, 458, 459, 460, 461, 462, 463, 464,
465, 466, 467, 468, 469, 470, 471, 472, 473, 474, 475, 476,
477, 478, 479, 480, 481, 482, 483, 484, 485, 486, 487, 488,
489, 490, 491, 492, 493, 494, 495, 496, 497, 498, 499, 500,
501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 512,
513, 514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524,
525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535, 536,
537, 538, 539, 540, 541, 542, 543, 544, 545, 546, 547, 548,
549, 550, 551, 552, 553, 554, 555, 556, 557, 558, 559, 560,
561, 562, 563, 564, 565, 566, 567, 568, 569, 570, 571, 572,
573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584,
585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596,
597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608,
609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620,
621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 632,
633, 634, 635, 636, 637, 638, 639, 640, 641, 642, 643, 644,
645, 646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656,
657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668,
669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680,
681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692,
693, 694, 695, 696, 697, 698, 699, 700, 701, 702, 703, 704,
705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716,
717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728,
729, 730, 731, 732, 733, 734, 735, 736, 737, 738, 739, 740,
741, 742, 743, 744, 745, 746, 747, 748, 749, 750, 751, 752,
753, 754, 755, 756, 757, 758, 759, 760, 761, 762, 763, 764,
765, 766, 767, 768, 769, 770, 771, 772, 773, 774, 775, 776,
777, 778, 779, 780, 781, 782, 783, 784, 785, 786, 787, 788,
789, 790, 791, 792, 793, 794, 795, 796, 797, 798, 799, 800,
801, 802, 803, 804, 805, 806, 807, 808, 809, 810, 811, 812,
813, 814, 815, 816, 817, 818, 819, 820, 821, 822, 823, 824,
825, 826, 827, 828, 829, 830, 831, 832, 833, 834, 835, 836,
837, 838, 839, 840, 841, 842, 843, 844, 845, 846, 847, 848,
849, 850, 851, 852, 853, 854, 855, 856, 857, 858, 859, 860,
861, 862, 863, 864, 865, 866, 867, 868, 869, 870, 871, 872,
873, 874, 875, 876, 877, 878, 879, 880, 881, 882, 883, 884,
885, 886, 887, 888, 889, 890, 891, 892, 893, 894, 895, 896,
897, 898, 899, 900, 901, 902, 903, 904, 905, 906, 907, 908,
909, 910, 911, 912, 913, 914, 915, 916, 917, 918, 919, 920,
921, 922, 923, 924, 925, 926, 927, 928, 929, 930, 931, 932,
933, 934, 935, 936, 937, 938, 939, 940, 941, 942, 943, 944,
945, 946, 947, 948, 949, 950, 951, 952, 953, 954, 955, 956,
957, 958, 959, 960, 961, 962, 963, 964, 965, 966, 967, 968,
969, 970, 971, 972, 973, 974, 975, 976, 977, 978, 979, 980,
981, 982, 983, 984, 985, 986, 987, 988, 989, 990, 991, 992,
993, 994, 995, 996, 997, 998, 999, 1000]

Uncluttered:

> numbers = (1..1000).collect { |i| i }; nil
 => nil 

When you search for something with grep, you sometimes need some context for the search results. Use the following arguments for that:

grep -B 2 foo bar.txt # 2 lines before every match
grep -A 3 foo bar.txt # 3 lines after every match
grep -C 1 foo bar.txt # 1 line before and after every match
grep -n 1 foo bar.txt # 1 line before and after every match

GitHub has introduced compare view about half a year ago. It basically is a nice frontend to git diff. You can specify a start and an end point for the diff. This can be commit hashes, tag or branch names:

http://github.com/<USER>/<REPO>/compare/[<START>...]<END>