The Shri Rudram (Sanskrit श्री रुद्रम्), to which the Chamakam (चमकम्) is added by scriptural tradition. During Pradosham (fast for Lord Shiva), people chant the Rudram when doing abishekam for Lord Shiva. I can still hear my brother chanting the Rudram while he does the abishekam. The following video is Rudram Chamakam chanted in Devanaagiri (Sanskrit)
Srirudram, also known as Rudraprasna, is a hymn devoted to lord Shiva. It ispart of the Yajur Veda and one of the greatest of the Vedic hymns. Sri Rudram is in two parts. The first part, chapter 16 of the Yajurveda, is known as Namakam because of the repeated use of the word “Namo” in it. The second part, chapter 18 of the Yajurveda, is known as chamakam because of the repeated use of the words “Chame”.
Rudram is divided into 11 sections called Anuvakas. In the first Anuvaka, Rudra is asked to turn away his Ghora rupa (fierce appearance) and to please keep his and his followers’ weapons at bay. Having been pacified, Rudra is requested to
destroy the sins of those for whom it is being chanted.
Apart from being a hymn devoted Lord Shiva, Srirudram also contains may hidden secrets in coded format. For example the verses contain coded instructions for preparing various ayurvedic medicines.
This first Anuvaka is chanted to destroy all sins, obtain leadership and divine benevolence, protection from famine, freedom from fear, obtain food, and protect cows, for absence from untimely fear of death, of tigers, thieves, from monsters, devils, demons. It is also chanted as a shield (kavaca) for virulent fever, to cure diseases, fetal disorders, absolution from evils stars and bad karma, for the fulfillment of ones desires, sumptuous rainfall, family
protection, blessings with good children, fulfillment of all material desires and the destruction of enemies.
In the second Anuvaka, Rudra is prayed to as one who pervades the earth and as the green foliage and heritage of medicinal herbs. He is asked to loosen the bonds of samsara (illusion). This Anuvaka is chanted for the destruction of
enemies, possession of wealth, getting kingdom (getting Job) and possession of intelligence.
In the third Anuvaka Rudra is described as the Lord of thieves who exists in everything. He is Sarvatma; the self of all. In this context, we who are unenlightened have stolen the immortal status of the Self and replaced it with
our own limited conception of ego. And in turn it is Rudra who will come and steal our ignorance from us, restoring us to our natural status of enlightenment. This Anuvaka is also chanted for the cure of diseases.
In the fourth Anuvaka, Rudra is described as the creator and worker of all kinds. He is the cause of both the significant and minor. This Anuvaka is chanted for the cure of tuberculosis, diabetics and leprosy.
In the fifth Anuvaka Rudra’s existence in running waters is praised and his five activities are described (creation of the universe, preservation of it, destruction at the time of Pralaya, bondage in ignorance and the release of moksha).
In the sixth Anuvaka Rudra is identified with time (Kalarupa). He is described as the source of the different worlds, Shrutis (Vedas) and its essence in Vedanta. The fifth and sixth Anuvakas are chanted for the expansion of one’s
own assets, victory against enemies, blessings for a son with the stature of Rudra, avoidance of a miscarriage and easy childbirth, averting difficult astrology and protection of one’s own son.
In the seventh Anuvaka his all-pervading presence in waters, rains, clouds, storms and its various forms are described. This Anuvaka is chanted for the increase of intelligence, improvement of health, wealth, progeny, clothes, cows, sons, education, lands, longevity and obtaining liberation.
In the eighth Anuvaka Rudra is described as He who illumines other Gods and confers powers on them. He is seen as ever present in holy rivers and He who can absolve all sins. This Anuvaka is chanted for the destruction of enemies and possession of ones own kingdom (lands).
In the ninth Anuvaka the strength and power his attendants is celebrated because they illumine the gods and the world and control the forces of the universe. This Anuvaka is chanted for obtaining gold, a good wife, a job, and the blessings of a son who will be devoted to Lord Shiva.
In the tenth Anuvaka Rudra is again asked to shed his fury and shower benevolence by his displaying his Pinaka bow without arrows and to gracefully appear with his tiger skin on his body with pleasing countenance ready to shower
boons upon his devotees. This Anuvaka is chanted for possession of wealth, cure of diseases, removal of fear, getting rid of the enmity of powerful people, absence of fear from all living beings, having the vision of Bhairava (Shiva in
his most fearful aspect), absence from dangers and fears, blessings and the absolution of sins.
In the eleventh Anuvaka Rudra’s accomplishments are profusely praised and his benevolence is invoked with unconditional salutations. This Anuvaka is chanted for blessings of one’s progeny, the enhancement of longevity, visiting of sacred places, and acquiring knowledge of past, present and future.
After praying and identifying Rudra with everything in the Namakam, the Chamakam is recited, in which the devotee identifies himself with Lord Shiva and asks him to give him everything he that’s needed in life.