Satguru (Sanskrit: सदगुरू) does not merely mean true guru. The term is distinguished from other forms of gurus, such as musical instructors, scriptural teachers, parents, and so on. The Sadguru is a title given specifically only to an enlightened rishi/sant whose life's purpose is to guide initiated shishya along the spiritual path, the summation of which is the realization of the Self through realization of God, who is omnipresent. A Satguru has some special characteristics that are not found in any other types of Spiritual Guru.
There are 4 types of Satguru:Types of Satguru
Nitya Anadi Satguru - He is the Eternal Satguru and has been addressed as Sukrit Deo, Atri, Jyoti, Aj and Sanatan in the Vedas. He has also been mentioned in the Upanishads as Amanava Purusha (Superhuman being). He can take a human form at his will.
Swayamsiddha Satguru - Existent through himself (rest in oneself, happy in oneself, creating oneself)
Abhayassiddha Satguru - With the quality of fearlessness.
Parampara Satguru - With a Guru lineage.
The recommendation says that the first and the foremost qualification of the True Master (Satguru) is that he must have known the True Lord (God) himself.
He is the real Sadhu, who can reveal the form of the Formless to the vision of these eyes;
of all enjoyments.
A real preceptor is one who can produce blissful sensation in the body of the disciple by their sight, touch, or instructions.
According to Sivaya Subramuniyaswami, a Hindu Sadguru is always a sanyasis, an unmarried renunciate, but not all writers include this stricture.Tukaram, a Hindu Sadguru, is known to have had a family, and Moinuddin Chishti also had children. Satguru Kabir had a son, Kamal, who was very devout.
Meher Baba equated worship of the Satguru with worship of God: "Consciously or unconsciously, directly or indirectly, each and every creature, each and every human being — in one form or the other — strives to assert individuality. But when eventually man consciously experiences that he is Infinite, Eternal and Indivisible, then he is fully conscious of his individuality as God, and as such experiences Infinite Knowledge, Infinite Power and Infinite Bliss. Thus Man becomes God, and is recognized as a Perfect Master, Sadguru, or Kutub. To worship this Man is to worship God."