【Tips】FileMagic用gemインストール時に発生しうるエラーへの対処

問題：ruby-filemagic gem インストールの失敗

入力

gem install ruby-filemagic -v '0.7.2'

出力

ERROR:  Error installing ruby-filemagic:
        ERROR: Failed to build gem native extension.

    current directory: /home/【ユーザー名】/.anyenv/envs/rbenv/versions/2.4.5/lib/ruby/gems/2.4.0/gems/ruby-filemagic-0.7.2/ext/filemagic
/home/【ユーザー名】/.anyenv/envs/rbenv/versions/2.4.5/bin/ruby -r ./siteconf20190315-389-smjtdo.rb extconf.rb
checking for -lgnurx... no
checking for magic_open() in -lmagic... no
*** ERROR: missing required library to compile this module
*** 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/【ユーザー名】/.anyenv/envs/rbenv/versions/2.4.5/bin/$(RUBY_BASE_NAME)
        --with-magic-dir
        --without-magic-dir
        --with-magic-include
        --without-magic-include=${magic-dir}/include
        --with-magic-lib
        --without-magic-lib=${magic-dir}/lib
        --with-gnurx-dir
        --without-gnurx-dir
        --with-gnurx-include
        --without-gnurx-include=${gnurx-dir}/include
        --with-gnurx-lib
        --without-gnurx-lib=${gnurx-dir}/lib
        --with-gnurxlib
        --without-gnurxlib
        --with-magiclib
        --without-magiclib

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

  /home/【ユーザー名】/.anyenv/envs/rbenv/versions/2.4.5/lib/ruby/gems/2.4.0/extensions/x86_64-linux/2.4.0-static/ruby-filemagic-0.7.2/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /home/【ユーザー名】/.anyenv/envs/rbenv/versions/2.4.5/lib/ruby/gems/2.4.0/gems/ruby-filemagic-0.7.2 for inspection.
Results logged to /home/【ユーザー名】/.anyenv/envs/rbenv/versions/2.4.5/lib/ruby/gems/2.4.0/extensions/x86_64-linux/2.4.0-static/ruby-filemagic-0.7.2/gem_make.out

環境

本記事における環境

• Windows Subsystem for Linux (WSL)
  • Ubuntu 18.04 LTS
• anyenv
  • rbenv 1.1.1-39-g59785f6
    • ruby 2.4.5p335 (2018-10-18 revision 65137) [x86_64-linux]

Ubuntu（Debian系）以外の環境の場合

補足に記述。

原因：FileMagicライブラリ

native extension用のFileMagicライブラリが未インストール。

解決方法

sudo apt install libmagic-dev
gem install ruby-filemagic -v '0.7.2'

補足

CentOS等Fedora系、Gentoo Linux、OS X（Mac）については以下の通り。
Debian系におけるsudo apt install libmagic-devコマンドを下記のものにそれぞれ置き換える。

Fedora系

sudo yum install file-devel

Gentoo

sudo emerge sys-libs
sudo emerge libmagic

OS X

brew install libmagic

参考文献

• blackwinter/ruby-filemagic