shell - Ansible 命令模块显示 '|' 是非法字符

Question

我正在使用 Ansible 部署我的项目，并尝试检查是否安装了指定的包，但我在执行该任务时遇到问题，这是任务:

- name: Check if python-apt is installed
  command: dpkg -l | grep python-apt
  register: python_apt_installed
  ignore_errors: True

问题是这样的:

$ ansible-playbook -i hosts idempotent.yml

PLAY [lxc-host] *************************************************************** 

GATHERING FACTS *************************************************************** 
ok: [10.0.3.240]

TASK: [idempotent | Check if python-apt is installed] ************************* 
failed: [10.0.3.240] => {"changed": true, "cmd": ["dpkg", "-l", "|", "grep", "python-apt"], "delta": "0:00:00.015524", "end": "2014-07-10 14:41:35.207971", "rc": 2, "start": "2014-07-10 14:41:35.192447"}
stderr: dpkg-query: error: package name in specifier '|' is illegal: must start with an alphanumeric character
...ignoring

PLAY RECAP ******************************************************************** 
10.0.3.240                 : ok=2    changed=1    unreachable=0    failed=0 

为什么这个字符'|'是非法的。

Answer 1

来自文档:

command - Executes a command on a remote node

The command module takes the command name followed by a list ofspace-delimited arguments. The given command will be executed on allselected nodes. It will not be processed through the shell, sovariables like $HOME and operations like "<", ">", "|", and "&" willnot work (use the shell module if you need these features).

shell - Executes a commands in nodes

The shell module takes the command name followed by a list of space-delimited arguments.It is almost exactly like the command module but runs the commandthrough a shell (/bin/sh) on the remote node.

因此你必须使用shell: dpkg -l | grep python-apt.