I installed data_mapper for a Sinatra project. Curious, why is it when I do gem install brew, I can $ which brew and get the path of its location and can't for data_mapper? This works for some gems and doesn't for others.
我为Sinatra项目安装了data_mapper。好奇，为什么当我做宝石安装brew时，我可以$ brew酿造并获取其位置的路径而不能用于data_mapper？这适用于某些宝石，而不适用于其他宝石。
How do I verify a gem is installed properly? Would checking the version assure the gem is downloaded correctly?
如何验证宝石安装是否正确？检查版本会确保gem正确下载吗？
2 个解决方案
#1
34
General solution
一般解决方案
Try gem list to get the list of gems that are installed.
尝试使用gem list获取已安装的gem列表。
To test for a particular gem, you can use -i with a regex: gem list -i "^gem_name$". (Credit to Timo in the comments for this technique.)
要测试特定的gem，可以使用-i和正则表达式：gem list -i“^ gem_name $”。 （在对这项技术的评论中感谢蒂莫。）
Particular solution for OP
OP的特殊解决方案
If you can't find data_mapper, it may be that the gem name is different from what you expect.
如果找不到data_mapper，可能是gem名称与您的期望不同。
Also, if you're just doing which brew to find brew, you aren't finding the gem called brew, you're finding the location of the brew executable. Try gem which brew instead.
此外，如果您正在使用brew查找brew，您没有找到名为brew的gem，您将找到brew可执行文件的位置。试试brew而不是brew。
EDIT:
编辑：
If you're looking for data_mapper by doing which data_mapper, you probably won't find it. which is a unix program for finding unix executables, and data_mapper probably doesn't have one.
如果您正在通过执行哪个data_mapper来查找data_mapper，您可能无法找到它。这是一个用于查找unix可执行文件的unix程序，而data_mapper可能没有。
Since your goal is to verify a gem is installed with the correct version, use gem list. You can limit to the specific gem by using gem list data_mapper.
由于您的目标是验证使用正确版本安装gem，请使用gem list。您可以使用gem list data_mapper限制特定的gem。
To verify that it's installed and working, you'll have to try to require the gem and then use it in your code.
要验证它是否已安装并正常工作，您必须尝试使用gem，然后在代码中使用它。
#2
33
In case you want to use the check in a script, this gives a better output (true or false) and appropriate exit code:
如果您想在脚本中使用检查，则会提供更好的输出（true或false）和适当的退出代码：
gem list -i <gem_name>
Alternatively add the version option:
或者添加版本选项：
gem list -i <gem_name> -v version
#1
34
General solution
一般解决方案
Try gem list to get the list of gems that are installed.
尝试使用gem list获取已安装的gem列表。
To test for a particular gem, you can use -i with a regex: gem list -i "^gem_name$". (Credit to Timo in the comments for this technique.)
要测试特定的gem，可以使用-i和正则表达式：gem list -i“^ gem_name $”。 （在对这项技术的评论中感谢蒂莫。）
Particular solution for OP
OP的特殊解决方案
If you can't find data_mapper, it may be that the gem name is different from what you expect.
如果找不到data_mapper，可能是gem名称与您的期望不同。
Also, if you're just doing which brew to find brew, you aren't finding the gem called brew, you're finding the location of the brew executable. Try gem which brew instead.
此外，如果您正在使用brew查找brew，您没有找到名为brew的gem，您将找到brew可执行文件的位置。试试brew而不是brew。
EDIT:
编辑：
If you're looking for data_mapper by doing which data_mapper, you probably won't find it. which is a unix program for finding unix executables, and data_mapper probably doesn't have one.
如果您正在通过执行哪个data_mapper来查找data_mapper，您可能无法找到它。这是一个用于查找unix可执行文件的unix程序，而data_mapper可能没有。
Since your goal is to verify a gem is installed with the correct version, use gem list. You can limit to the specific gem by using gem list data_mapper.
由于您的目标是验证使用正确版本安装gem，请使用gem list。您可以使用gem list data_mapper限制特定的gem。
To verify that it's installed and working, you'll have to try to require the gem and then use it in your code.
要验证它是否已安装并正常工作，您必须尝试使用gem，然后在代码中使用它。
#2
33
In case you want to use the check in a script, this gives a better output (true or false) and appropriate exit code:
如果您想在脚本中使用检查，则会提供更好的输出（true或false）和适当的退出代码：
gem list -i <gem_name>
Alternatively add the version option:
或者添加版本选项：
gem list -i <gem_name> -v version