Lingachara is the worship of Supreme GOD in the form of Ishtalinga ಇಷ್ಟಲಿಂಗ - the amorphous representation of Supreme GOD. The devotee must remain faithful to Ishtalinga ಇಷ್ಟಲಿಂಗ throughout his/her life and must perform daily worship in order to elevate himself/herself to Muktatma (i.e. relief from the rebirth cycle of mundane world).
LINGĀCHĀRA: [ಲಿಂಗಾಚಾರ] consists mainly worshipping the ISHTALINGA and nothing else. One must take a vow at the time of initiation that one worships ishta-linga thrice a day and neither believes nor worships other gods and goddesses. A breach of this vow is indicative not only of the disloyalty of the devotee to the Ishtalinga, but also disbelief in doctrines of Lingayathism.
When the linga becomes a property on your body
it is impossible to bow
to an installed god.
Would intercourse with another
abandoning one's own man
Even as the god is your on palm
if you bow to one installed on the earth
Koodalasangamadeva will dump you in hell. -Guru Basava/4 
God is one, names are many.
A chaste wife has just one husband.
Should she desire another,
he will chop her ears and nose off.
What would you say then of those
who relish leftovers of many gods, Koodalasangamadeva? 230 
Only one husband for a wife with faith, and
only one god for a devotee with faith.
The company of other gods is not done.
The desire for alien gods is not done.
If Koodalasangamadeva comes to know,
he will sever your nose. -241 
Why go to holy places
when you have the linga on your body?
If the linga on your body touches installed linga,
I cannot say which is great, which small!
People perished not knowing
the absolute that is beyond the reach of speech.
Your head becomes pure
by bowing to the jangama;
your hand becomes pure
by worshipping the linga.
Do not show me a breaker of vows,
who, ignoring the linga on the body,
bows to a distant linga,
Koodala Chennasangayya. -653 
The highest form of Lingāchār is expressed when a devotee convinces himself that he is a vehicle of Parashiva and that whatever he does, thinks, speaks or experiences is for Linga (Parashiva), and not for himself or his family's sake.
 Number indicates at the end of each Vachana is from the book "Vachana", pub: Basava Samiti Bangalore 2012.