如何从Ruby程序内部调用shell命令?然后如何将这些命令的输出返回到Ruby中?
当前回答
我最喜欢的是Open3
require "open3"
Open3.popen3('nroff -man') { |stdin, stdout, stderr| ... }
其他回答
我最喜欢的是Open3
require "open3"
Open3.popen3('nroff -man') { |stdin, stdout, stderr| ... }
在这些机制之间进行选择时需要考虑的一些事情是:
你只是想要stdout还是 也需要stderr ?甚至 分离出来吗? 你的产出有多大?你想要 将整个结果保存在内存中? 你想读一些你的吗 在子进程静止时输出 跑步吗? 你需要结果代码吗? 你需要一个Ruby对象吗 表示流程并允许您 按需杀死它?
您可能需要简单的反撇号(' ')、system()和IO。popen到成熟的Kernel.fork/Kernel。执行IO。pipe和IO.select。
如果子进程执行时间过长,您可能还想在混合过程中加入超时。
不幸的是,这在很大程度上取决于情况。
这个解释是基于我的一个朋友写的带注释的Ruby脚本。如果您想改进脚本,请在链接中进行更新。
首先,请注意,当Ruby调用shell时,它通常调用/bin/sh,而不是Bash。在所有系统上/bin/sh不支持某些Bash语法。
以下是执行shell脚本的方法:
cmd = "echo 'hi'" # Sample string that can be used
Kernel#` , commonly called backticks – `cmd` This is like many other languages, including Bash, PHP, and Perl. Returns the result (i.e. standard output) of the shell command. Docs: http://ruby-doc.org/core/Kernel.html#method-i-60 value = `echo 'hi'` value = `#{cmd}` Built-in syntax, %x( cmd ) Following the x character is a delimiter, which can be any character. If the delimiter is one of the characters (, [, {, or <, the literal consists of the characters up to the matching closing delimiter, taking account of nested delimiter pairs. For all other delimiters, the literal comprises the characters up to the next occurrence of the delimiter character. String interpolation #{ ... } is allowed. Returns the result (i.e. standard output) of the shell command, just like the backticks. Docs: https://docs.ruby-lang.org/en/master/syntax/literals_rdoc.html#label-Percent+Strings value = %x( echo 'hi' ) value = %x[ #{cmd} ] Kernel#system Executes the given command in a subshell. Returns true if the command was found and run successfully, false otherwise. Docs: http://ruby-doc.org/core/Kernel.html#method-i-system wasGood = system( "echo 'hi'" ) wasGood = system( cmd ) Kernel#exec Replaces the current process by running the given external command. Returns none, the current process is replaced and never continues. Docs: http://ruby-doc.org/core/Kernel.html#method-i-exec exec( "echo 'hi'" ) exec( cmd ) # Note: this will never be reached because of the line above
这里有一些额外的建议: $ ?,与$CHILD_STATUS相同,如果使用反勾号、system()或%x{},则访问最后一个系统执行命令的状态。 然后你可以访问exitstatus和pid属性:
$?.exitstatus
更多阅读请参见:
http://www.elctech.com/blog/i-m-in-ur-commandline-executin-ma-commands http://blog.jayfields.com/2006/06/ruby-kernel-system-exec-and-x.html http://tech.natemurray.com/2007/03/ruby-shell-commands.html
上面的答案已经非常棒了,但是我真的很想分享下面的总结文章:“在Ruby中运行Shell命令的6种方法”
基本上,它告诉我们:
# exec内核:
exec 'echo "hello $HOSTNAME"'
System和$?:
system 'false'
puts $?
Backticks ():
today = `date`
IO # execlp:
IO.popen("date") { |f| puts f.gets }
Open3#popen3—stdlib:
require "open3"
stdin, stdout, stderr = Open3.popen3('dc')
Open4#popen4—一个宝石:
require "open4"
pid, stdin, stdout, stderr = Open4::popen4 "false" # => [26327, #<IO:0x6dff24>, #<IO:0x6dfee8>, #<IO:0x6dfe84>]
最简单的方法是:
reboot = `init 6`
puts reboot