VirtualBox 4 USB support in Linux

Download VirtualBox Oracle VM VirtualBox Extension Pack and install it by VirtualBox → File → Preferences... → Extensions → Add package.

Then grant vboxusers groups access to the USB device filesystem:

$ grep 108 /etc/group
vboxusers:x:108:
$ vim /etc/fstab
usbfs  /proc/bus/usb  usbfs  auto,busgid=108,busmode=0775,devgid=108,devmode=0664  0  0

Password protected GRUB Legacy

Add password into the main GRUB section to password protect the interactive operations (i.e. editing menu entries and entering the command-line interface). Optionally add lock into a menu entry to prevent it from executing if no valid password is provided by the user.

$ grub-md5-crypt 
Password: 
Retype password: 
$1$K0Kh10$OmQNQOthH8jppDFQ5TYx5/

$ chmod 600 /boot/grub/menu.lst
$ vim /boot/grub/menu.lst
default 0
...
password --md5sum $1$K0Kh10$OmQNQOthH8jppDFQ5TYx5/

title Linux
kernel ...

title OpenBSD
lock
kernel ...

Create a svn tag from trunk

svn mkdir http://svn.example.com/project/tags -m "release directory"
svn copy http://svn.example.com/project/trunk \
         http://svn.example.com/project/tags/1.0 -m "release 1.0"

Nicer Oracle Date Output

Oracle date output including full year, month, day, hours, minutes and seconds:

SQL> alter session set nls_date_format = 'yyyy-mm-dd hh24:mi:ss';
SQL> alter session set nls_timestamp_format = 'yyyy-mm-dd hh24:mi:ss';
SQL> select foo_date from bar_table where rownum <= 1;

FOO_DATE
-------------------
2012-01-01 01:02:03

Tunneling VNC connection

Connect to a VNC server listening on localhost on port 5901 (+1 than usual) using tunneling:

vncviewer -via yourusername@remotemachine localhost:1

Identify old RPM packages in a directory

	#!/usr/bin/env perl
	# [2011-03-15] viliam.pucik@gmail.com
	# Prints all old (SRC) RPM packages from specified directory.
	# Assumed package format: name-version-release.distribution_optionalpatch.suffix.rpm
	#
	# Use case:
	#
	# $ ls test/
	# glibc-2.12-1.7.el6_0.3.src.rpm glibc-2.12-1.7.el6_0.4.src.rpm glibc-2.12-1.7.el6.src.rpm
	# $ ./oldrpm.pl test/
	# glibc-2.12-1.7.el6.src.rpm glibc-2.12-1.7.el6_0.3.src.rpm
	use strict;
	use warnings;
	if ( scalar @ARGV < 1 ) {
	print "usage: oldrpm.pl <dir>\n";
	exit 1;
	}
	opendir my $dh, $ARGV[0] or die $!;
	my @rpms = grep { /\.rpm$/ } readdir $dh;
	close $dh;
	my %names;
	map { /([\w\-\+]+)-[^-]+-[\d\.]+/, push @{ $names{$1} }, $_ } @rpms;
	for ( sort keys %names ) {
	next if scalar @{ $names{$_} } < 2;
	my $pkg = my $version = my $release = my $patch = undef;
	for ( @{ $names{$_} } ) {
	/[\w\-\+]+-([^-]+)-([\d\.]+)[^_]+_([\d\.]+)/;
	my $_3 = ( defined $3 ) ? $3 : '';
	/[\w\-\+]+-([^-]+)-([\d\.]+)/;
	if ( !defined $pkg
	|| $version lt $1
	|| ( $version eq $1 && $release lt $2 )
	|| ( $version eq $1 && $release eq $2 && $patch lt $_3 ) ) {
	$pkg = $_;
	$version = $1;
	$release = $2;
	$patch = $_3;
	}
	}
	# commented alternative output
	#print "-"x20, "\n";
	for ( @{ $names{$_} } ) {
	#print;
	#print " *" if ( $_ eq $pkg );
	#print "\n";
	print "$_ " if $_ ne $pkg;
	}
	}

view raw oldrpm.pl hosted with ❤ by GitHub

How to build RPM packages as a regular user

Install the necessary packages as root:

sudo yum install rpmdevtools rpm-build redhat-rpm-config

Initialize the directory hierarchy for your custom build RPM packages as a regular user:

rpmdev-setuptree

Optionally add additional attributes into ~/.rpmmacros, e.g.:

echo '%packager Your Name <your.name@foo.bar>' >> ~/.rpmmacros

Use rpmbuild to build RPM from a source RPM or from a SPEC file:

rpmbuild --rebuild package.src.rpm
rpmbuild -bb package.spec