gemコマンドで初めてツールをインストールしようとしたところ、以下のエラーが発生。
#gem install zsteg
Building native extensions. This could take a while...
ERROR: Error installing zsteg:
ERROR: Failed to build gem native extension.current directory: /var/lib/gems/2.3.0/gems/rainbow-2.2.2/ext
/usr/bin/ruby2.3 mkrf_conf.rbcurrent directory: /var/lib/gems/2.3.0/gems/rainbow-2.2.2/ext
/usr/bin/ruby2.3 -rubygems /usr/share/rubygems-integration/all/gems/rake-12.0.0/exe/rake RUBYARCHDIR=/var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/rainbow-2.2.2 RUBYLIBDIR=/var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/rainbow-2.2.2
/usr/bin/ruby2.3: No such file or directory -- /usr/share/rubygems-integration/all/gems/rake-12.0.0/exe/rake (LoadError)rake failed, exit code 1
Gem files will remain installed in /var/lib/gems/2.3.0/gems/rainbow-2.2.2 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/rainbow-2.2.2/gem_make.out
原因としてはエラー文にバッチリ記載されている通り、
/usr/bin/ruby2.3: No such file or directory -- /usr/share/rubygems-integration/all/gems/rake-12.0.0/exe/rake (LoadError)
とのことだったので、
#gem install rake
でrakeを先にインストールした後で再度実行したところ、無事にインストールできました。
#gem install zsteg
Building native extensions. This could take a while...
Successfully installed rainbow-2.2.2
Fetching: zpng-0.2.5.gem (100%)
Successfully installed zpng-0.2.5
Fetching: zsteg-0.1.2.gem (100%)
Successfully installed zsteg-0.1.2
Parsing documentation for rainbow-2.2.2
Installing ri documentation for rainbow-2.2.2
Parsing documentation for zpng-0.2.5
Installing ri documentation for zpng-0.2.5
Parsing documentation for zsteg-0.1.2
Installing ri documentation for zsteg-0.1.2
Done installing documentation for rainbow, zpng, zsteg after 1 seconds
3 gems installed