Linux Ask!

Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.

Sep 262011
 

Enable Perl strict mode to restrict unsafe constructs

Answer:

In Perl, you can enforce using the strict mode to reduce the chance of nasty error, e.g.

$foo = 'bar';
print $foo;

If you run the above problem, it is completely valid.

# perl test.pl
bar

However, if you use the strict pragma

use strict;

$foo = 'bar';
print $foo;

And run the program again..

# perl test.pl
Global symbol "$foo" requires explicit package name at test.pl line 3.
Global symbol "$foo" requires explicit package name at test.pl line 4.
Execution of test.pl aborted due to compilation errors.

Since the $foo is not declared before the first use, so the compilation stopped. In modern Perl developements, it is recommended to alwasys use the strict pragma in order to write a better and maintainable program.

To fix the problem, you need to use the my keyword, e.g.

use strict;

my $foo = 'bar';
print $foo;

And run the program again. (Thanks Jeroen for the suggestion)

Sep 142011
 

Install NodeJS in Linux

Answer:

In order to install NodeJS in Linux, the recommended way is compile from source and install it.

# wget http://nodejs.org/dist/node-v0.4.11.tar.gz
# tar zxf node-v0.4.11.tar.gz
# cd node-v0.4.11
# ./configure
# sudo make && make install

Now you can type node to enter the node's REPL