(1) Execute方法

$irb

>> exec 'echo "hello $HOMENAME"'

(2) System方法

>>system 'echo "hello $HOMENAME"'

(3) 反引号

>> today= `date`

(4) open3#popen3

>>stdin,stdout,stderr=open3.popen3('dc')

(5) IO#popen

>>IO.popen("date") {|f| puts f.gets}

(6) open#popen4

>> require "open4"

=>true

>>pid,stdin,stdout,stderr=open4::popen4 "false"