$ gem install subtitle_it
----------------
Fetching: colorize-0.8.1.gem (100%)
Successfully installed colorize-0.8.1
Fetching: charlock_holmes-0.7.3.gem (100%)
Building native extensions. This could take a while...
ERROR: Error installing subtitle_it:
ERROR: Failed to build gem native extension.
current directory: /home/john/.rvm/gems/ruby-2.3.1/gems/charlock_holmes-0.7.3/ext/charlock_holmes
/home/john/.rvm/rubies/ruby-2.3.1/bin/ruby -r ./siteconf20161022-26947-c6bcdh.rb extconf.rb
checking for main() in -licui18n... no
checking for main() in -licui18n... no
***************************************************************************************
*********** icu required (brew install icu4c or apt-get install libicu-dev) ***********
***************************************************************************************
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/home/john/.rvm/rubies/ruby-2.3.1/bin/$(RUBY_BASE_NAME)
--with-icu-dir
--without-icu-dir
--with-icu-include
--without-icu-include=${icu-dir}/include
--with-icu-lib
--without-icu-lib=${icu-dir}/lib
--with-icui18nlib
--without-icui18nlib
--with-icui18nlib
--without-icui18nlib
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/home/john/.rvm/gems/ruby-2.3.1/extensions/x86_64-linux/2.3.0/charlock_holmes-0.7.3/mkmf.log
extconf failed, exit code 1
Gem files will remain installed in /home/john/.rvm/gems/ruby-2.3.1/gems/charlock_holmes-0.7.3 for inspection.
Results logged to /home/john/.rvm/gems/ruby-2.3.1/extensions/x86_64-linux/2.3.0/charlock_holmes-0.7.3/gem_make.out