检查是否使用ruby脚本安装了rpm

Question

I'm trying to rewrite some bash scripts and one of the sections checks if certain rpm's are installed on the system with a basic if statement

if rpm -qa | grep rpmnamehere; then
     do stuff

I want to do something similar in ruby, but am pretty new to this and not sure where to look in the documentation.

Thanks

Answer 1

You can invoke shell command in ruby script, and save output in variable

a = %x{rpm -qa | grep rpmnamehere}
puts a

or only invoke command

`rpm -qa | grep rpmnamehere`

so, I think you can solve your problem like this

unless `rpm -qa | grep rpmnamehere`.empty?
  # do stuff
end

Answer 2

You can do something like this in ruby code:

if system "rpm -qa | grep rpmnamehere"
   #additional ruby statements
end

the system call will return true or false depend if the system command is successful or not.