Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Install RubyOnRails in Ubuntu
Answer:
In the last article, we talked how to install Ruby in Ubuntu. Now, we are going to install a very popular web framework for Ruby - RubyOnRails.
Firstly, you need to install RubyGems, a gem is a packaged Ruby application or library.
# sudo apt-get install rubygems
Then, we use the gem command to install rails.
# sudo gem install rails
That's all.
Install Ruby in Ubuntu
Answer:
To install Ruby under Ubuntu, you need to type the commands below:
# sudo apt-get install ruby-full build-essential
The above command will install more than the Ruby interpreter, but they are useful when you want to play with RubyOnRails later.
Initialize MySQL Data Directory
Answer:
When you compiled a new MySQL server, it is needed to create a default data directory.
To do so, you need to use the mysql_install_db command.
# bin/mysql_install_db --user=mysql \
--basedir=/opt/mysql/mysql \
--datadir=/opt/mysql/mysql/data
The --datadir is the target directory for storing the database files, where --basedir specifies the MySQL server base directory.
Reference: http://dev.mysql.com/doc/refman/5.0/en/mysql-install-db.html
Write to the middle of a file in Perl
Answer:
To write to the middle of a text file, can be easily performed by Perl.
Assume the file has 10 lines, you want to replace the 5th line:
#!/usr/bin/perl
use strict;
use Tie::File;
my $file = 'foo.txt';
tie @array, 'Tie::File', $file or die "Cannot open $file \n";
@array[4] = "Replaced!\n";
That's easy?
What are PHP variable variables?
Answer:
A variable variable takes the value of a variable and treats that as the name of a variable.
Example:
<?php
$foo = "bar";
$bar = "foo";
echo $foo; // print "bar"
echo $$foo; // print "foo", since $foo = "bar", thus $$foo = $bar
Reference: http://il2.php.net/manual/en/language.variables.variable.php
