Guy's been a colonel forever. What does he have to do to get a promotion? Run the country, or something?
Unlike some other military revolutionaries, Gaddafi did not promote himself to the rank of general upon seizing power, but rather accepted a ceremonial promotion from captain to colonel and has remained at this rank since then.
While at odds with Western military ranking for a colonel to rule a country and serve as Commander-in-Chief of its military, in Gaddafi's own words Libya's society is "ruled by the people", so he needs no more grandiose title or supreme military rank.
Gaddafi's decision to remain a colonel is not a new concept among military coup leaders; Gamal Abdel Nasser remained a colonel after seizing power in Egypt, and Jerry Rawlings held no military rank higher than flight lieutenant while leader of Ghana. In the same fashion El Salvador was ruled by Lieutenant Colonel Oscar Osorio (1950-1956), Lieutenant Colonel José María Lemus (1956-1960), and Lieutenant Colonel Julio Adalberto Rivera (1962-1967).
The previous Ethiopian leader Mengistu Haile Mariam Haile Mariam remains Colonel since he was ousted by EPRDF.