( !'which npm' ) 在 PHP 脚本中是什么意思?

问题描述

( !'which npm' ) 在下面的代码中是什么意思?

What does ( !'which npm' ) mean in the following code?

if ( !'which npm' ) {
  die(
        'You need to install NPM!' . PHP_EOL
  );
}

这里是 GITHUB 完整文件的链接:WPBP/生成器/bin/wpbp-生成器

Here is a link to the complete file from GITHUB: WPBP/generator/bin/wpbp-generator

推荐答案

它检查硬编码字符串是否falsey.这将始终是 false.

It checks whether a hardcoded string is falsey. Which will always be false.

这个逻辑看起来有点无意义.我怀疑作者更想写:

This logic looks a bit meaningless. I suspect the author rather wanted to write:

if (!`which npm`)

反引号运算符将命令作为shell命令执行，这有点意思.

The backtick operator executes the command as shell command, which makes a bit more sense.

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