When you get “You don’t have write permissions for the /usr/bin directory”

in your installation with gem, you can solve the issue with the option -n /usr/local/bin.

Many internet sources said so. Of cource it works.

I thought this is a good chance to look a little more about gem install options.

We can get the information by ‘gem help install’ in the terminal.

Several useful options

I found several useful options in the help document as follows.

install command options

-v, --version VERSION: Specify version of gem to install

    --[no-]prerelease: Allow prerelease versions of a gem to be installed. (Only for listed gems)

-i, --install-dir: DIR Gem repository directory to get installed gems

-n, --bindir DIR: Directory where executables are located

common options

-h, --help: Get help on this command (same as gem help command)
-V, --[no-]verbose: Set the verbose level of output
-q, --quiet: Silence command progress meter
    --silent: Silence RubyGems output
    --config-file FILE: Use this config file instead of default (maybe useful for the batch-like jobs)
    --backtrace: Show stack backtrace on errors