/Library/Ruby/Gems/2.3.0/gems/cocoapods-1.5.3/lib/cocoapods/command.rb:118:in `git_version': Fail...

/Library/Ruby/Gems/2.3.0/gems/cocoapods-1.5.3/lib/cocoapods/command.rb:118:in git_version': Failed to extract git version fromgit --version("xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun\n") (RuntimeError) from /Library/Ruby/Gems/2.3.0/gems/cocoapods-1.5.3/lib/cocoapods/command.rb:130:inverify_minimum_git_version!'
from /Library/Ruby/Gems/2.3.0/gems/cocoapods-1.5.3/lib/cocoapods/command.rb:49:in run' from /Library/Ruby/Gems/2.3.0/gems/cocoapods-1.5.3/bin/pod:55:in<top (required)>'
from /usr/local/bin/pod:22:in load' from /usr/local/bin/pod:22:in<main>'

百度出来一堆垃圾，做个记录，就是检查一下xcode是否安装命令行工具。
去Xcode - > Preferenced - > Locations并选择Command Line Tools,查看是否选择了当前xcode版本，就可以了