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'sudo gem install' or 'gem install' and gem locations
...rse than just gem install is because it installs the gems for ALL USERS as root. This might be fine if you're the only person using the machine, but if you're not it can cause weirdness.
If you decide you want to blow away all your gems and start again it's much easier, and safer, to do so as a no...
NullPointerException accessing views in onCreate()
...ent onCreateView(), calling findViewById() on the inflated fragment layout rootView:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
View somethin...
What do all of Scala's symbolic operators mean?
...ode has three automatic imports:
// Not necessarily in this order
import _root_.java.lang._ // _root_ denotes an absolute path
import _root_.scala._
import _root_.scala.Predef._
The first two only make classes and singleton objects available. The third one contains all implicit conversions a...
How to delete the contents of a folder?
...bolic links, should work on Windows as well.
import os
import shutil
for root, dirs, files in os.walk('/path/to/folder'):
for f in files:
os.unlink(os.path.join(root, f))
for d in dirs:
shutil.rmtree(os.path.join(root, d))
...
SQL Server 2005 How Create a Unique Constraint?
...NIQUE (ColumnName1,ColumnName2, ColumnName3, ...)
The query supported by MySQL / SQL Server / Oracle / MS Access.
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How to define custom configuration variables in rails
...
# config/initializers/load_config.rb
APP_CONFIG = YAML.load_file("#{Rails.root}/config/config.yml")[Rails.env]
# application.rb
if APP_CONFIG['perform_authentication']
# Do stuff
end
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Django rest framework nested self-referential objects
...ution works but the count output of my serializer is wrong. It only counts root nodes. Any ideas? It's the same with djangorestframework-recursive.
– Lucas Veiga
May 3 '17 at 1:29
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How to check if a process id (PID) exists
...wo ways:
Lets start by looking for a specific application in my laptop:
[root@pinky:~]# ps fax | grep mozilla
3358 ? S 0:00 \_ /bin/sh /usr/lib/firefox-3.5/run-mozilla.sh /usr/lib/firefox-3.5/firefox
16198 pts/2 S+ 0:00 \_ grep mozilla
All examples now will look...
Sort points in clockwise order?
...
+1: No atan(), no square root, and even no divisions. This is a good example of computer graphics thinking. Cull off all the easy cases as soon as possible, and even in the hard cases, compute as little as possible to know the required answer.
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Given two directory trees, how can I find out which files differ by content?
...les in subdirs, for example rsync --options /usr /bin /var /sbin /lib /old_root will effectively compare current root / (by specifying all subdirs in it) and /old_root (containing for example some older backup of /), which is something diff -r can't do. And if you assume that files with same size, ...