在centos7服务器上安装oxidized-web时，一直提示错误：

Building native extensions. This could take a while...
ERROR:  Error installing oxidized-web:
        ERROR: Failed to build gem native extension.

    current directory: /usr/local/lib/ruby/gems/2.7.0/gems/charlock_holmes-0.7.7/ext/charlock_holmes
/usr/local/bin/ruby -I /usr/local/lib/ruby/site_ruby/2.7.0 extconf.rb
checking for -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=/usr/local/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=${icu-dir}/lib
        --with-icu-i18n-config
        --without-icu-i18n-config
        --with-pkg-config
        --without-pkg-config
        --with-icu-io-config
        --without-icu-io-config
        --with-icu-uc-config
        --without-icu-uc-config
        --with-icui18n-dir
        --without-icui18n-dir
        --with-icui18n-include
        --without-icui18n-include=${icui18n-dir}/include
        --with-icui18n-lib
        --without-icui18n-lib=${icui18n-dir}/lib
        --with-icui18nlib
        --without-icui18nlib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /usr/local/lib/ruby/gems/2.7.0/extensions/x86_64-linux/2.7.0-static/charlock_holmes-0.7.7/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /usr/local/lib/ruby/gems/2.7.0/gems/charlock_holmes-0.7.7 for inspection.
Results logged to /usr/local/lib/ruby/gems/2.7.0/extensions/x86_64-linux/2.7.0-static/charlock_holmes-0.7.7/gem_make.out
[root@hfebnetbap01 ~]# brew install icu4c
-bash: brew: command not found

此处提示“brew install icu4c or apt-get install libicu-dev”，发现是系统缺少lib库，安装完毕后重新使用gem安装即可；

缺少的库安装：

yum install libicu-devel
yum install pango pango-devel
yum install cairo cairo-devel