Libyans are marking the anniversary of the uprising that led to the overthrow of Col Muammar Gaddafi after his rule of more than 40 years.
Celebrations are planned in towns and cities across the country and have been under way for days in the eastern city of Benghazi, where the revolt began.
But the anniversary comes amid fears of continuing instability.
Hundreds of militias are roaming the country unimpeded and observers point to an institutional void in Libya.
Libyan interim leader Mustafa Abdul Jalil on Thursday vowed a tough response to anyone who threatened national security during Friday’s celebrations.
‘Curly, we’re sorry!’
Friday 17 February marks one year since the first major demonstration against Col Gaddafi’s rule in Benghazi, which became the rebel stronghold.
The bloody uprising quickly spread around the country and led eventually to Nato’s military intervention in the conflict. Col Gaddafi was killed in his hometown of Sirte on 20 October.
There will be fireworks and – no doubt – plenty of shooting in the air.
The interim government says there will be no military parades, as a mark of respect for those who lost their lives during the revolution.
But that won’t apply to the “thuwwar”, the brigades of former rebel fighters who have yet to hand over their weapons. They are a law unto themselves, answerable only to their own commanders.
And that is where the problem lies: Libya’s new rulers are having limited success in persuading these battle-hardened men to join any of the national security forces. Disputes between rival militias are frequent and often violent.
And there are fears that unless they are controlled and disarmed soon, Libya could slide back into oppression and instability.
No official celebrations have been announced, as a mark of respect for the thousands who died in the battle for Libya, but locally arranged events are taking place around the country.
On Thursday, residents set off firecrackers, honked car horns and flashed “V for victory” signs in Benghazi, reports said.
Hundreds gathered at the square now called Freedom Square to chant anti-Gaddafi slogans – including, reported AFP news agency, the sarcastic chant “Curly, we’re sorry!”
Later on Friday leading figures in the interim government are set to attend a special commemorative function.
In the capital Tripoli, roadblocks have been set up to search for any attempt to disrupt the festivities.
Tripoli resident Naima Misrati told AFP that traffic police and former rebels were distributing leaflets, warning people against thinking of carrying out attacks, which read: “We cannot bring back the buried man [Gaddafi] but we can send you to him.”
Ms Misrati said she was celebrating “freedom for the first time” which the revolution had brought her.
“I have no words to describe my happiness. There is joy everywhere in Tripoli,” she said.
In a TV address on the eve of the anniversary, Mr Abdul Jalil insisted his government had “opened our arms to all Libyans, whether they supported the revolution or not”.
“But this tolerance does not mean we are incapable of dealing with the stability of our country,” he warned, according to AFP.
“We will be tough towards people who threaten our stability. The thuwwar [brigades of former rebel fighters] are ready to respond to any attack aimed at destabilising” the country,” Mr Abdul Jalil reportedly said.
However, according to the BBC’s Gabriel Gatehouse in Tripoli, the government’s lack of control over the thuwwar is seen by many as one of central factors in Libya’s continued instability.