Rhodesia's quiet capital, basking these days in the sunny glories of early autumn, is a city in uneasy limbo - hung between war and peace, between waning white colonial control and coming black majority rule.

Sturdy-looking white soldiers with military crewcuts, many in camouflage fatigues and rakish berets, check their weapons at the door when they arrive at a downtown hotel for a few hours' respite from the frustrating guerrilla hunt in the countryside.

A smiling young white couple settles into the front seat of a late-model Jaguar, looking for all the world like they are off on a tryst - except that the man is carrying a holstered gun. Outsidie the main towns, local people say, guerilla ambush is now an ever present danger.

Uncertainties have flourished here since March Ian Smith, for 12 years the symbol of Rhodesian white residence to black power, made a pact with three black leaders that is meant to lead to black-dominated government by the end of the year.

But the arrangement, known variously as the "internal," "interim" or "transitional" settlement, has evidently only emboldened the guerrillas of the patriotic front, an alliance of black factions not included in Smith's deal.

After skirmishing with the white-led army for several years, the guerrillas are said to be expanding their operations now that the whites are finally giving up the reins. White officers are confused and demoralized, military experts say, and the blacks in the Rhodesian army are being pressed into action with a minimum of training, unlike the past when they were prepared for any challenge.

"Nobody is quite sure what they are fighting for anymore," said Allan Sovory, leader of Rhodesia's tiny Liberal Party, who is a counterinsurgency buff.

There are about two dozen Western reporters in and out of Salisbury to cover the unfolding story. Many of them spent time in Indochina and the comparisons flow easily, if not always precisely.

The insecurity in the countryside, natives whose allegiance is to government by day and guerrillas by night: "I'd say it's about where Vietnam was in 1964, just before the U.S. got involved," said one old hand.

FOR ALL, the tensions, the posters warning to beware of bombs and the security checks at most buildings and stores, life in Sallisbury goes on, in many ways as it has for decades.

On Tuesday night, the Meikles, one of the city's better hotels, played host to score of pretty girls, their well-scrubbed escorts and proud parents. The occasion was the annual ball of Salisbury's modeling school, where young ladies are taught how to comport themselves. One difference with the past was that several of the girls were black.

At another hotel, many of the rooms were taken by participants at an international convention of blind bowlers. On April 29, the Foreign Shorthair Cat Society will be holding its second championship show at the Garden Club Hall. The Rhodesia Herald has seven pages of classifieds, jobs offered and wanted, houses for sale and sought.

"The Rhodesian stock market was firm in a more active session," the newspaper reported.

In a populalr restaurant, a group of nurses finishing their shift, gathered at a champagne breadfast for one of their number who was getting married. They sang "Here Comes the Bride" and she cried.

While guerrillas bedded down in the bush, other blacks waited wearily at a Salisbury bus stop after long days on the job for the long, crowded trip home to the townships on the city periphery where they are consigned to live.

"HERE TO SEE the minister?" queried the prim secretary in the clipped British tones of so many Sallisbury whites. Then the permanent undersecretary of the department arrived, tall and proper in a wooden suit despite the climbing thermometer.

The door opens and the minister rises. He is Elliot Gabellah, black and a follower of the Rev. Ndabaningi Sithole, one of the three blacks in the new Executive Council. Gabellah is co-minister of information and foreign affairs in the new setup, with two white counterparts.

Gabellah's office is bare and his duties unclear, but the secretary and civil servant, retainers of the white government, treat him like the boss, nodding approvingly as he speaks:

"There has never been a time since 1890," he said "when blacks could have a voice here . . . Now we have what we couldn't get out of Smith before. The chaps in the bush are fighting for the same thing. Why should they go on?"

What about U.S. wariness of the new government? Is there a possibility, as the United States fears, that the government will end up in a civil war with its opponents? Is the West a reliable ally?

Gabellah sidesteps sensitive questions. "I don't want to speak ill of crocodiles," he remarks, "when I am about to cross the river."

Elsewhere at the Foreign Ministry, a white official made no bones about how he regarded the unfriendly policies of the Carter administration. He was a postcard picture of Jimmy Carter upside down on the wall.

"I can't stand his smile," the official said.

IAN SMITH ONCE said there would be no black majority rule in Rhodesia for a thousand years. Once he said there would be no black rule in his lifetime. Now he is handing over the country to blacks. What changed his mind?

"It was the meeting I had in Pretoria [South Africa] in September 1976 with Henry Kissinger," Smith said in an interview at his prime ministerial office, "where he told me this was the best deal they could produce.

"We were impressed with his straightforward, honest approach. We had heard a lot of stories and reports about this gentleman, that we had to be on our guard against him. But we never found ourselves in that position.

"If we didn't accept this [proposal] . . . those few friends we had left in the world . . . would no longer be able to go on doing this . . . We came to the conclusion that 'Well, this is it.' The time had come for us to make up our minds. We could no longer go on being out of step with the whole of the rest of the world over the question of majority rule.

"Nowhere else in the world did anybody go along with sort of thing we believe in."