The -f operator returns true only if the file exists.

只有在文件存在时，- f操作符才返回true。

youdao

The sound emerges from the f-holes, a pair of elegantly curled slits either side of the bridge.

声音从f孔传出，两个卷曲精致的f孔位于琴码两侧。

youdao

The F-35B is the first aircraft to combine stealth with short takeoff/vertical landing (STOVL) capability and supersonic speed.

F-35B战斗机是第一架结合隐形和短距/垂直起降（STOVL）能力的超音速战斗机。

youdao

They attend the F.Edward Hebert School of Medicine of the Uniformed Services University of the Health Sciences in Bethesda,Maryland.

VOA: special.2010.07.13

There is a striking parallel here in that the group one elements have a tendency to want to give up electrons, F Cl Br whereas the fluorine, chlorine, bromine, have a tendency to attract electrons.

这儿有高度的相似性,每个组都有,失去电子的趋势的，相反的，则是有得电子的趋势。

麻省理工公开课 - 固态化学导论课程节选

There was a huge old insurrection called the Fronde, f-r-o-n-d-e.

有一起被称为投石党运动的起义

耶鲁公开课 - 欧洲文明课程节选

But it would be shortsighted to shoot down the F-22 because of governmental operational deficiencies.

FORBES: Fact And Comment

Some experts said it was possible that even if the reduced staffing persisted, the F.

FORBES: Flights Delayed Amid Furloughs Of Air Controllers

By that time, after midnight, Elliot and Susan would have driven up the F.

NEWYORKER: Another Manhattan