VirtualDJ is not available for Linux but there are some alternatives that runs on Linux with similar functionality. The best Linux alternative is Mixxx, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to VirtualDJ and seven of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to VirtualDJ are TerminatorX, BpmDj, DJPlay and YOU.DJ.
TerminatorX is a realtime audio synthesizer. This software allows scratching audio data (wav,ogg,mp3, etc.) the way hiphop-DJs scratch on vinyl records. It features multiple turntables, realtime LADSPA effects, a sequencer and MIDI interface.
TerminatorX vs VirtualDJ opinions
Most users think TerminatorX is a great alternative to VirtualDJ.
BpmDj is a program that can be used to DJ. It works under Linux and plays Mp3's/Ogg's. It has a fully automatic BPM counter. It can determine the sound color. It has a full fledged QT based interface. It will help you manage a large amount of songs.
MIXO is a cross platform Music Library service that allows DJs to manage their own music on any device with Import & Export options for all the major DJ Performance Software. It syncs in app to Google Drive & Dropbox for use on iOS & Android.