NEW YORK, AUG. 21 -- The Dow Jones average of 30 industrials inched upward to a new high today as the stock market closed out an erratic session with modest gains.

Tobacco stocks ranked among the day's standout performers following a court ruling in favor of the industry on a key point in a product liability case.

Dow Jones's average of 30 blue chips rose 2.71 to 2709.50, bringing its net gain for the week to 24.07 points. Volume on the New York Stock Exchange came to 189.58 million shares, against 196.57 million in the previous session.

Before the market opened, the Labor Department reported that the consumer price index rose 0.2 percent in July. The figure came in below most advance estimates on Wall Street, and reinforced hopes that inflation would remain subdued.

Even with that positive news, however, some traders proceeded warily, awaiting the last trading late Friday of a series of expiring stock options and futures contracts.

There was some talk that this might produce heightened volatility in the market as professionals engaged in computer trading strategies closed out their positions. As it turned out, the market closed without any notable disruptions.

In addition, analysts said investors remained in an edgy mood over continued pressure on the dollar in foreign exchange.

The tobacco stocks jumped ahead after a federal appeals court in Atlanta ruled that American Brands can raise the issue of health warnings in advertisements and on packaging in defending itself against a product liability suit. American Brands shares gained 2 7/8 to 55 3/8; RJR Nabisco 2 3/4 to 64 1/4, and Philip Morris 4 3/4 to 111 1/2.

ACM Government Income Fund was the most active NYSE-listed issue, rising 1/4 to 12.

Smithkline Beckman followed, falling 5 3/4 to 65 3/4 on news that the FDA has approved a generic form of Smithkline Beckman's antihypertensive drug, Dyazide. In trading on the American Stock Exchange, Bolar, which makes the generic version, jumped 6 3/8 to 35 1/8. It said the drug should boost company sales by more than $10 million annually.

AT&T was third, dropping 5/8 to 34 5/8. Elsewhere in the blue-chip group, IBM eased 1/8 to 174 5/8, General Electric slid 3/8 to 65 1/2, General Motors dropped 1 7/8 to 92, Merck dropped 1 1/4 to 206 1/4, Eastman Kodak snapped on 1 1/4 to 103 and American Express rose 1/4 to 38 3/4.

High-technology issues strengthened. Digital Equipment jumped 5 1/4 to 190, Cray Research rose 3 to 116 7/8, Unisys added 1 to 47 5/8, Compaq Computer added 1 to 57 1/2, Tandy added 1 to 49 5/8 and Hewlett-Packard jumped 1 3/4 to 68 3/8.

National Semiconductor rose 1/4 to 15, Motorola climbed 2 3/4 to 67 5/8 and Texas Instruments jumped 1 3/8 to 71 3/8.

Manpower Inc. rose 3 3/4 to 81 3/4. The company said its management will recommend that directors agree to an $82.50-a-share takeover bid from the London-based Blue Arrow PLC.

Advancing issues just barely outnumbered declines on the NYSE, with 803 up, 776 down and 439 unchanged. The exchange's composite index added .47 to 187.51.

Standard & Poor's index of 400 industrials rose 1.36 to 392.34, and S&P's 500-stock composite index was up 1.06 at 335.90.

The Nasdaq composite index for the over-the-counter market climbed 2.45 to 455.20.