In a dusty street of this capital's Ridina quarter, a semicircle of small boys sat this afternoon at the feet of their schoolmaster, reciting verses from the Koran, sheltered from Chad's scorching sun by a tree.

Ismail Abukar, the elderly teacher, said his classes had not been interrupted by the two months of fighting up north and out east. "And it is quiet again," said the white-bearded Abukar during a brief break in the lesson. "For the moment, praise be to Allah, there is peace."

Several Chadians said they became nervous in the early weeks of the fighting when the Libyan-backed rebel forces had reached Abeche in the east. Many thought they would have to flee the capital. If the battle reached here, it would be the fourth time in four years.

But today the inhabitants went about their Sunday affairs, seemingly unconcerned about the heated battles that had been fought 625 miles northeast at Faya Largeau or 400 miles east at Abeche.

Several said that with the positioning of French paratroops at Abeche yesterday, and the announcement today that others will enter Salal Monday, the two routes to Ndjamena are now blocked to the antigovernment forces.

Since the latest fighting began in late June, the repeated military thrusts of the rebels led by ex-president Goukouni Oueddei have been to seize the western and eastern routes to Ndjamena from the northern town of Faya Largeau, the dissidents' present stronghold.

In the to-and-fro battles that have raged across the Chadian landscape over 18 years of civil war, the capture of Ndjamena, now a city of about 200,000, has always been the main objective.

As a result, the buildings downtown are pocked by bullets and the cathedral is burned down. Whichever of the six armies--among 11 political factions--roaming Chad that controlled Ndjamena could claim it was the legitimate government.

But the current phase of the war seemed distant to Ibrahim Abakar, 35, who was doing a brisk business at his dry-goods stall in the central market.

"The small crowd you see is normal for a Sunday morning," said Abakar as he looked out from his booth of corrugated metal at the steady stream of robed shoppers. "They will grow fewer as the sun gets hotter. It is not like this because of the war."

"We are accustomed to the fighting," he said. "Believe me, people are relaxed now that it does not look like Libyan leader Muammar Qaddafi is coming here."

Abakar said he has survived the years of fighting as a small trader. He, his wife and four children avoided having to flee the city when one faction or another captured it.

In early 1979, the forces of the current president, Hissene Habre, battled ex-president Felix Malloum's army for control of Ndjamena. The civil war then was clearer in its purpose--a war between Afro-Arab Moslems from north and east against the southern blacks, who are Christian or follow African religions. The blacks then controlled the government and had since independence in 1960.

Other Moslem factions came in from Chad's Sahara Desert and semi-arid Sahel region to join Habre in the fight against Malloum's government. Malloum, defeated, fled to exile in neighboring Nigeria. The Moslem factions formed a weak coalition government that included the southern blacks and agreed on Goukouni as an interim president. Habre was made defense minister.

Early in 1980, fighting erupted here between Habre's force and the five armies lined up in support of Goukouni. Nine months later, a Libyan Army force moved in through northern Chad at Goukouni's invitation and Habre's forces fled east into Sudan.

When the Libyans withdrew a year later, Habre began to push west from Abeche and captured Ndjamena from Goukouni's coalition in June of last year. Now Goukouni, supported by the other factional leaders and by Libya, is trying to push south from Faya Largeau to retake Ndjamena from Habre.

The French have sided with President Habre. With French troops in position alongside Habre's in Abeche and soon in Salal, it is as yet unclear whether Goukouni, with Qaddafi's help, will try to battle his way to the capital.

The French paratroops are supposed to give "instructions" to Habre's forces on defending the approaches. But the French forces, who will be in the two main battle areas, have orders to fight back if they are fired on.

A French military source indicated that the French troops will have antiaircraft capabilities, but declined to specify what type of weapons. Qaddafi's Soviet-made bombers and fighters have had complete command of the battle zones until now, a major advantage in the war against Habre.

It was also learned today that troops sent by Zaire--aboard U.S. planes--to support Habre are in Abeche and Moussoro, south of Salal.

"Everyone here was worried at the beginning, when the rebels reached Abeche," said the merchant Abakar. But they held it only a short time before retreating north in the face of a government counteroffensive. "I was afraid we'd have more fighting in Ndjamena, Abakar said.

"But our worries for the moment have ended, although the war has not ended, I don't believe Qaddafi will want to come here now, because he has lost too much materiel and Allah will stop him."

Mahamut Hassan, 43, a truck driver from Abeche, stopped to talk outside Ndjamena's large sandstone mosque. "Things are quiet now, so we relax and go about our business," said Hassan over the drone of the second day of French cargo flights into the nearby airport.

The dozen flights today brought jeeps and light armored cars from French bases in the Central African Republic, a French military source said tonight.

Hassan said he has fled Ndjamena three times--to Abeche, to Sudan and into northern Nigeria--during the battles for the capital. He nervously disavowed any knowledge of domestic politics, however, as did Abakar.

"These matters are too complicated for a simple truck driver like me," Hassan said with a smile. "But for the moment, there is peace here and we will let Allah take care of tomorrow."