你是否还在因为使用 brew install 时卡在 update 阶段而捶胸顿足，甚至一度想放弃brew，那么今天你的救星来啦~
问题
使用 brew install 时会触发 brew update，而update阶段主要是进行homebrew-cask 和 homebrew-core 及一些其他相关依赖的更新，这些依赖都托管在GitHub，由于国内网络访问GitHub本身就比较慢，做大文件下载的速度可想而知会更慢。
初步分析
使用brew update –verbose观察update过程：
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
| brew update --verbose
Checking if we need to fetch /usr/local/Homebrew...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/caskroom/homebrew-fonts...
Fetching /usr/local/Homebrew...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask...
Checking if we need to fetch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core...
Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask...
Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core...
remote: Enumerating objects: 337, done.
remote: Counting objects: 100% (337/337), done.
remote: Compressing objects: 100% (88/88), done.
remote: Total 298 (delta 221), reused 287 (delta 210), pack-reused 0
Receiving objects: 100% (298/298), 50.91 KiB | 39.00 KiB/s, done.
Resolving deltas: 100% (221/221), completed with 39 local objects.
From https://github.com/Homebrew/homebrew-core
65a45a9..583b7f1 master -> origin/master
remote: Enumerating objects: 179429, done.
remote: Counting objects: 100% (179429/179429), done.
remote: Compressing objects: 100% (56607/56607), done.
Receiving objects: 4% (7628/177189), 1.48 MiB | 8.00 KiB/s
|
可以发现在从 GitHub fetch 资源时是最罪恶根源。
解决方案两步走
step one. 更换Homebrew源
目前国内比较好用的brew源有很多，比较推荐使用清华大学开源软件镜像站的，以下是详细配置：
1
2
3
4
5
6
7
8
9
10
11
12
13
|
git -C "$(brew --repo)" remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/brew.git
git -C "$(brew --repo homebrew/core)" remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-core.git
git -C "$(brew --repo homebrew/cask)" remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-cask.git
git -C "$(brew --repo homebrew/cask-fonts)" remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-cask-fonts.git
git -C "$(brew --repo homebrew/cask-drivers)" remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-cask-drivers.git
git -C "$(brew --repo homebrew/core)" remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/linuxbrew-core.git
|
配置完成后，可以到对应的目录下查看git remote配置，如：
1
2
| cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core
git remote -v
|
看到显示为如下的结果说明已经配置成功：
1
2
| origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-core.git (fetch)
origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-core.git (push)
|
step two. 更换 Homebrew-bottles 镜像（影响软件下载速度）
临时替换
1
| export HOMEBREW_BOTTLE_DOMAIN=https://mirrors.tuna.tsinghua.edu.cn/homebrew-bottles
|
永久替换
1
2
| echo 'export HOMEBREW_BOTTLE_DOMAIN=https://mirrors.tuna.tsinghua.edu.cn/homebrew-bottles' >> ~/.bash_profile
source ~/.bash_profile
|
至此，已经完成了brew源的切换，可以运行 brew update 测试是否正常。
参考链接：
异常情况
homebrew-versions 相关报错
如果在执行brew update时出现如下报错：
1
2
| fatal: could not read Username for 'https://github.com': terminal prompts disabled
Error: Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-versions failed!
|
说明你的brew版本太老旧了，在新版中homebrew-versions已经被移除了，可以执行如下命令来移除它：
1
| brew untap homebrew/versions
|
参考链接：Error running brew update
homebrew-cask-fonts 相关报错
当执行上述的git -C "$(brew --repo homebrew/cask-fonts)" remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-cask-fonts.git 命令时，如出现下方错误，则可以忽略错误，并不执行该命令，不影响最终体验。
1
| fatal: Cannot change to '/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-fonts': No such file or directory
|