Linux: Kill a process matching a partial name
This is useful to kill processes like ruby my-script.rb:
pkill -f my-script.rb
With great power comes great responsibility.
Related cards:
Calling a helper method with the same name as your current partial
Partials always define a local variable with the same name as themselves. E.g. when you are in _recent_users.html.erb, a local variable recent_users will be defined and overshadow any helper method that is also called recent_users().
If you...
Linux: Running a single unique instance of command + arguments
run-one is a wrapper script that won't run the given command while another instance of it is running. Is brings several utility commands that offer similar behavior.
NAME
run-one - run just one instance at a time of some command and...
Kill a dead SSH shell
If a SSH shell dies (from timeout for example), you cannot kill it with the usual CTRL-C or CTRL-Z. Instead, press
[ENTER]~.
(That is ENTER TILDE PERIOD).
Get the current layout's name in a view or partial
This returns the name (including path) of your current layout:
response.layout
=> "layouts/admin" # inside views that are using the 'admin' layout
You most likely do not need the full path, so go ahead and do this:
File.basename(res...
An obscure kernel feature to get more info about dying processes
This post will describe how I stumbled upon a code path in the Linux kernel which allows external programs to be launched when a core dump is about to happen. I provide a link to a short and ugly Ruby script which captures a faulting process, runs...
Hack of the day: Find all classes that define a method with a given name
If (for some reason that you don't want to ask yourself) you need to know all classes that define a method with a given name, you can do it like this:
def classes_defining_method(method_name)
method_name = method_name.to_sym
Objec...
Test that a hash contains a partial hash with RSpec
To test whether a hash includes an expected sub-hash:
expect(user.attributes).to match(hash_including('name' => 'Bruce Wayne'))
expect(User).to receive(:create!).with(hash_including('name' => 'Bruce Wayne'))
Linux: Running a program with a different locale than your default
When your system is not running on English, you may sometimes want to run some applications and not use your system locale.
Use cases are scripts that parse output, or just using the (possibly) more common English labels or error messages. Here is...
Help me, there is a zombie process!
Here is a good explanation for zombie processes.
Quote:
If you have zombie processes it means those zombies have not been waited for by their parent (look at PPID displayed by ps -l).
You h...
Inspecting a live Ruby process
How to get a backtrace from a running Ruby process:
Ruby 2.6
# First, find out the PID of your Ruby process (e.g. passenger-status)
$ sudo gdb -p PID
(gdb) call rb_eval_string("$stderr.reopen('/tmp/ruby-debug.' + Process.pid.to_s); $std...