其实很简单，执行这个命令: 酿造的医生

它会告诉你该怎么做，来修复权限问题，比如我的例子:

这就是问题所在:

Warning: The following directories are not writable by your user:
/usr/local/share/man/man5
/usr/local/share/man/man7

这就是解决方案:

You should change the ownership of these directories to your user.
  sudo chown -R $(whoami) /usr/local/share/man/man5 /usr/local/share/man/man7

如果你想要一个比毯子chown -R更有针对性的方法，你可能会发现这个fix-homebrew脚本很有用:

#!/bin/sh

[ -e `which brew` ] || {
    echo Homebrew doesn\'t appear to be installed.
    exit -1
}

BREW_ROOT="`dirname $(dirname $(which brew))`"
BREW_GROUP=admin
BREW_DIRS=".git bin sbin Library Cellar share etc lib opt CONTRIBUTING.md README.md SUPPORTERS.md"

echo "This script will recursively update the group on the following paths"
echo "to the '${BREW_GROUP}' group and make them group writable:"
echo ""

for dir in $BREW_DIRS ; do {
    [ -e "$BREW_ROOT/$dir" ] && echo "    $BREW_ROOT/$dir "
} ; done

echo ""
echo "It will also stash (and clean) any changes that are currently in the homebrew repo, so that you have a fresh blank-slate."
echo ""

read -p 'Press any key to continue or CTRL-C to abort.'

echo "You may be asked below for your login password."
echo ""

# Non-recursively update the root brew path.
echo Updating "$BREW_ROOT" . . .
sudo chgrp "$BREW_GROUP" "$BREW_ROOT"
sudo chmod g+w "$BREW_ROOT"

# Recursively update the other paths.
for dir in $BREW_DIRS ; do {
    [ -e "$BREW_ROOT/$dir" ] && (
        echo Recursively updating "$BREW_ROOT/$dir" . . .
        sudo chmod -R g+w "$BREW_ROOT/$dir"
        sudo chgrp -R "$BREW_GROUP" "$BREW_ROOT/$dir"
    )
} ; done

# Non-distructively move any git crud out of the way
echo Stashing changes in "$BREW_ROOT" . . .
cd $BREW_ROOT
git add .
git stash
git clean -d -f Library

echo Finished.

它不会对用户执行chmod操作，而是将homebrew使用的/usr/local中特定目录的写权限授予管理组(您可能属于该组)。它还会在执行之前准确地告诉你它打算做什么。

首先，使用MacOS Catalina，不再允许更改/usr/local的所有权的基本方法。例如:

$ sudo chown -R "$USER":wheel /usr/local
Password:
chown: /usr/local: Operation not permitted
$ sudo chown -R "$USER" /usr/local
chown: /usr/local: Operation not permitted
$ sudo chown -R $(whoami) /usr/local
chown: /usr/local: Operation not permitted

因此，上面常用的答案不能使用。然而，其次，退一步说，如果主要考虑的是安装或升级Homebrew，而不是想要更改/usr/local本身的权限，那么更改/usr/local的权限可能会太过了(就像用大锤锤钉子一样)。它会影响您的整个机器和其他软件可能也在使用/usr/local。例如，我在/usr/local中有maven和mySQL相关的文件。

一个更精确的解决方案是按照Homebrew GitHub站点上给出的说明安装Homebrew，即

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"

它将Homebrew安装在/usr/local中，而不改变/usr/local本身的所有权。相反，Cellar、Caskroom、Frameworks、Homebrew等都安装在/usr/local目录下。在我看来，这似乎是一个更优雅、更精确的解决方案。

我在卡特琳娜，我得到了这个错误:

touch: /usr/local/Homebrew/.git/FETCH_HEAD: Permission denied
touch: /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask/.git/FETCH_HEAD: Permission denied
fatal: Unable to create '/usr/local/Homebrew/.git/index.lock': Permission denied
fatal: Unable to create '/usr/local/Homebrew/.git/index.lock': Permission denied

我只需要把Homebrew目录翻个遍

sudo chown -R "$USER":admin /usr/local/Homebrew

对于像我一样降落在这里的人来说，第一选择是，按照这个建议去做:

brew doctor

这是最安全的方法，除此之外，它还建议我:

sudo chown -R $(whoami) /usr/local

这解决了权限问题。

OP这样做了，但显然没有得到上述建议;你可能会，从这里开始总是更好的，然后再寻找非平凡解如果它没有帮助的话。

所有这些建议都可能奏效。在最新版本的brew doctor中，有了更好的建议。

首先-通过在命令行中运行这个命令来修复你可能已经造成的/usr/local混乱:

sudo chown -R root:wheel /usr/local

然后获取路径的所有权，应该专门为这个用户:

sudo chown -R $(whoami) /usr/local/lib /usr/local/sbin /usr/local/var /usr/local/Frameworks /usr/local/lib/pkgconfig /usr/local/share/locale

所有这些信息都是可用的，如果你运行sudo brew update，然后阅读所有的警告和错误，你会遇到…