Can not install Cocoapods with RubyGem 2.7.1

Question

My Cocoapods did not work, therefore I did the following command:

1. run this bash script to remove all the relevant gems:

   for i in $( gem list --local --no-version | grep cocoapods );
   do 
       sudo gem uninstall $i; 
   done
   

2. delete ~/.cocoapods to remove the cache of podspecs.:

   rm -rf ~/.cocoapods/
   

3. update rubygem:

   sudo gem update --system
   

4. reinstall cocoapods:

   sudo gem install cocoapods
   

Then I got file permission deny error message in Step3 and Step 4:

Step3 error message:
...
...
Done installing documentation for rubygems-update after 0 seconds
Installing RubyGems 2.7.1
ERROR: While executing gem ... (Errno::EPERM)
Operation not permitted @ rb_sysopen - /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/gem

Step4 error message:
Fetching: cocoapods-core-1.3.1.gem (100%)
Successfully installed cocoapods-core-1.3.1
Fetching: cocoapods-deintegrate-1.0.1.gem (100%)
Successfully installed cocoapods-deintegrate-1.0.1
Fetching: cocoapods-downloader-1.1.3.gem (100%)
Successfully installed cocoapods-downloader-1.1.3
Fetching: cocoapods-plugins-1.0.0.gem (100%)
Successfully installed cocoapods-plugins-1.0.0
Fetching: cocoapods-search-1.0.0.gem (100%)
Successfully installed cocoapods-search-1.0.0
Fetching: cocoapods-stats-1.0.0.gem (100%)
Successfully installed cocoapods-stats-1.0.0
Fetching: cocoapods-trunk-1.3.0.gem (100%)
Successfully installed cocoapods-trunk-1.3.0
Fetching: cocoapods-try-1.1.0.gem (100%)
Successfully installed cocoapods-try-1.1.0
ERROR: While executing gem ... (Gem::FilePermissionError) You don't have write permissions for the /usr/bin directory.

I have limited knowledge about Linux/OSX file sysem, and do not know what was wrong.

Here are information about my computer:

1. OS:

   macOS High Sierra 10.13.1

2. Xcode:

   Version 9.0.1 (9A1004)
   I also have XCode 7.3.1 renamed as Xcode_7 in the Applications Folder

3. Environment path:

   echo $PATH
   

   /Library/Frameworks/Python.framework/Versions/3.4/bin:
   /usr/local/bin:
   /usr/bin:
   /bin:
   /usr/sbin:
   /sbin:
   /opt/X11/bin:
   /Applications/Server.app/Contents/ServerRoot/usr/bin:
   /Applications/Server.app/Contents/ServerRoot/usr/sbin

4. Homebrew:

   brew --version
   

   Homebrew 1.3.6
   Homebrew/homebrew-core (git revision 985b; last commit 2017-11-07)

   brew list
   

   cmake libxml2 ninja pkg-config readline wget gdbm libyaml openssl python3 sqlite xz

5. RubyGems:

   gem --version
   

   2.7.1

   gem list
   

   * LOCAL GEMS *
   activesupport (5.1.4, 4.2.10)
   bigdecimal (1.3.2, default: 1.2.8)
   CFPropertyList (2.3.5, 2.2.8)
   claide (1.0.2)
   colored2 (3.1.2)
   concurrent-ruby (1.0.5)
   did_you_mean (1.0.0)
   escape (0.0.4)
   fourflusher (2.0.1)
   fuzzy_match (2.1.0, 2.0.4)
   gh_inspector (1.0.3)
   i18n (0.9.1)
   io-console (0.4.6, default: 0.4.5)
   json (2.1.0, default: 1.8.3)
   libxml-ruby (3.0.0, 2.9.0)
   mini_portile2 (2.3.0)
   minitest (5.10.3)
   molinillo (0.6.4, 0.5.7)
   nanaimo (0.2.3)
   nap (1.1.0)
   net-telnet (0.1.1)
   netrc (0.11.0)
   nokogiri (1.5.6)
   power_assert (1.1.1)
   psych (2.2.4, default: 2.1.0)
   rake (12.2.1, 10.4.2)
   rdoc (5.1.0, default: 4.2.1)
   ruby-macho (1.1.0)
   rubygems-update (2.7.1)
   sqlite3 (1.3.11)
   test-unit (3.2.6)
   thread_safe (0.3.6)
   tzinfo (1.2.4)
   xcodeproj (1.5.3)

Answer 1

I think Hjalmar's answer does work. However I ended up use Homebrew to install Ruby, and everything works fine for me. Just type:

brew install ruby

in Terminal.

Answer 2

This ended up working for me.

Also got the Ruby reinstall error from running sudo gem update --system

ERROR:  While executing gem ... (Errno::EPERM)
            Operation not permitted @ rb_sysopen - 
        /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/gem

I then tried to execute the same command (sudo gem update --system) again and got Latest version already installed. Done.

Instead of running

sudo gem install cocoapods

try

sudo gem install -n /usr/local/bin cocoapods

Which ended up working for me! Didn't clean the previous cocoapods with the bash-script like you're doing in step 1 though but shouldn't make a difference as you do a reinstall.