Ansible command, Shell, Raw, expect, script, telnet[turn]

This paper mainly introduces several command modules of ansible, including:

• command-Execute commands on the remote node
• shell-Let the remote host execute the command under the shell process
• script-Executes the local script after it is delivered to the remote host
• raw-Perform low-level and dirty SSH commands
• expect-Execute commands and respond to prompts
• telnet-Perform low-level and dirty Telnet commands

Command Module Introduction

• commandThe module is used to run system commands on the given node, such as echo hello.
• It does not handle commands through the shell and therefore does not support$HOMEvariables like this and, as well,,<>|,;and&so on are not valid. That iscommand, you cannot use pipe characters in a module.

Module parameters

name		remarks
ChDir	No	CD to this directory before running command commands
Creates	No	If the file that corresponds to this parameter exists, do not run the command
Free_form	Yes	Scripts that need to be executed (no real parameter is Free_form)
Executable	No	Changing the shell used to execute the command should be the absolute path to the executable file.
Removes	No	If the file corresponding to this parameter does not exist, do not run the command, as opposed to the creates parameter
StdIn (added after 2.4)	No	Sets the stdin of the command to the specified value

Example

• List files under the specified directory

[[email protected] ~]# ansible test -m command -a "ls /root"172.20.21.120 | SUCCESS | rc=0 >>anaconda-ks.cfgtest.shwhoami.rst[[email protected] ~]# ansible test -m command -a "ls /root creates=test.sh"172.20.21.120 | SUCCESS | rc=0 >>skipped, since test.sh exists[[email protected] ~]# ansible test -m command -a "ls /root removes=test.sh1"172.20.21.120 | SUCCESS | rc=0 >>skipped, since test.sh1 does not exist

In this case, first change the directory to the root directory, and then see if test.sh exists, and if so, the command will not execute, and if not, execute the command.

As you can see here, the command must exist, but there is no parameter named Free_form parameter .

• Switch Directory execution commands

[[email protected] ~]# ansible test -m command -a "cat test.sh chdir=/root"172.20.21.120 | SUCCESS | rc=0 >>#!/bin/bashi=0echo $((i+1))[[email protected] ~]# ansible test -m command -a "sh test.sh chdir=/root"172.20.21.120 | SUCCESS | rc=0 >>1

• Cannot use pipe character

[[email protected] ~]# ansible test -m command -a "ls /root | grep test"172.20.21.120 | FAILED | rc=2 >>/root:anaconda-ks.cfgtest.shwhoami.rstls: 无法访问|: 没有那个文件或目录ls: 无法访问grep: 没有那个文件或目录ls: 无法访问test: 没有那个文件或目录non-zero return code

Precautions

• To run a command through the shell, for example,,<>etc.,|you actually need theshellmodule.
• commandThe module is more secure because it is not affected by the user's environment
• Starting with version 2.4, theexecutableparameters are removed. If you need this parameter, use the Shell module instead.
• For Windows nodes, usewin_commandmodules instead.

Introduction to Shell Modules

Allow the remote host to execute commands under the shell process to support shell features, such as pipelines. Almost the same as thecommandmodule, but is used when executing the command/bin/sh.

Module parameters

name	must-Choose	Notes
ChDir	No	CD to this directory before running command commands
Creates	No	If the file that corresponds to this parameter exists, do not run the command
Executable	No	Changing the shell used to execute the command should be the absolute path to the executable file.
Free_form	Yes	Scripts that need to be executed (no real parameter is Free_form)
Removes	No	If the file corresponding to this parameter does not exist, do not run the command, as opposed to the creates parameter
StdIn (added after 2.4)	No	Sets the stdin of the command to the specified value

Example

• Switch directories, execute commands and maintain output

[[email protected] ~]# ansible test -m shell -a "sh test.sh > result chdir=/root"172.20.21.120 | SUCCESS | rc=0 >>[[email protected] ~]# ansible test -m shell -a "cat result chdir=/root"172.20.21.120 | SUCCESS | rc=0 >>1

Precautions

• If you want to execute commands safely and reliably, usecommandmodules, which is also a best practice for writing playbook.

Introduction to the Script module

• scriptThe function of the module is to transfer the local script to the remote host after it executes
• The given script will be processed by the shell environment on the remote node
• scriptThe module does not require Python support on the remote system

Module parameters

name	must-Choose	Default Value	Optional Values	Notes
ChDir (added after 2.4)	No			CD to this directory before running command commands
Creates	No			If the file that corresponds to this parameter exists, do not run the command
Decrypt	No	yes	yes/no	This option controls the automatic decryption of source files that use vaults
Free_form	Yes			Local file path that requires script execution (no real parameter is Free_form)
Removes	No			If the file corresponding to this parameter does not exist, do not run the command, as opposed to the creates parameter

Example

• Executing scripts on the remote host

[[email protected] ~]# ansible test -m command -a "ls /root"
172.20.21.120 | SUCCESS | rc=0 >>
anaconda-ks.cfg
test.sh
whoami.rst

[[email protected] ~]# ansible test -m command -a "ls /root creates=test.sh"
172.20.21.120 | SUCCESS | rc=0 >>
skipped, since test.sh exists

[[email protected] ~]# ansible test -m command -a "ls /root removes=test.sh1"
172.20.21.120 | SUCCESS | rc=0 >>
skipped, since test.sh1 does not exist

Precautions

• In general, using ansible modules is better than push scripts
• When the script executes, the SSH connection plug-in is forced to be-tt伪ttyassigned.伪ttyswithout the stderr channel, all stderr are sent to the standard output. If you need standard output and standard error separation, use tocopymodule.

Introduction to RAW Modules

• rawModules are primarily used to perform some low-level, dirty SSH commands, rather than throughcommandmodules. Therawmodule is only available for the following two scenarios, the first of which is on older (Python 2.4 and earlier) hosts, and the other on any device that does not have Python installed (such as a router). In any other case, the useshellorcommandmodule is more appropriate.
• Likescriptmodules,rawmodules do not require Python on a remote system

Module parameters

name	must-Choose	Notes
Executable	No	Changing the shell used to execute the command should be the absolute path to the executable file.
Free_form	Yes	Scripts that need to be executed (no real parameter is Free_form)

Example

• Executing scripts on the remote host

[[email protected] ~]# ansible test -m command -a "cat test.sh chdir=/root"
172.20.21.120 | SUCCESS | rc=0 >>
#!/bin/bash
i=0
echo $((i+1))

[[email protected] ~]# ansible test -m command -a "sh test.sh chdir=/root"
172.20.21.120 | SUCCESS | rc=0 >>
1

Precautions

• If you want to execute commands safely and reliably, it is best to useshellorcommandmodules instead.
• If you are using raw from playbook, you may need to use thegather_facts: nodisable fact collection

Expect module introduction

• expectThe module is used to execute a command on the given node and respond to the prompt.
• It does not handle commands through the shell and therefore does not support$HOMEvariables like this and, as well,,<>|,;and&so on are not valid. That iscommand, you cannot use pipe characters in a module.

Usage requirements (on the host that executes the module)

• Python >= 2.6
• Pexpect >= 3.3

Module parameters

name	must-Choose	Default Value	Notes
ChDir	No		CD to this directory before running command commands
Command	Yes		Command Module Execution Command run
Echo	No		Whether to echo your response string
Responses	Yes		The expected string/regular expression and the string are mapped to respond. If the response is a list, successive matches will return a continuous response. The list feature is a new feature in 2.1.
Creates	No		If the file that corresponds to this parameter exists, do not run the command
Removes	No		If the file corresponding to this parameter does not exist, do not run the command, as opposed to the creates parameter
Timeout	No	30	Wait for the expected time in seconds

Example

• Executing scripts on the remote host

[[email protected] ~]# ansible test -m command -a "ls /root | grep test"
172.20.21.120 | FAILED | rc=2 >>
/root:
anaconda-ks.cfg
test.sh
whoami.rstls: Cannot access |: No such file or directory
ls: Cannot access grep: No such file or directory
ls: Cannot access test: No such file or directory non-zero return code

Precautions

• If you want to run a command through the shell (for example, you are using, and<>so on|), you must specify a shell in the command, for example/bin/bash -c "/path/to/something | grep else".
• Theresponseskey below is a Python regular expression match, with a prefix for case-insensitive searches?i.
• By default, if you encounter problems more than once, their string responses are repeated. If a continuous problem match requires a different response than a string response, use a list of strings as a response.
• expectModules are designed for simple scenarios, and for more complex requirements, you shouldshellconsiderscriptusing expect code in or modules

Introduction to the Telnet module

• expectThe module is used to perform some low-level and dirty Telnet commands, not through the module subsystem.
• It does not handle commands through the shell and therefore does not support$HOMEvariables like this and, as well,,<>|,;and&so on are not valid. That iscommand, you cannot use pipe characters in a module.

Module parameters

name	must-Choose	Default Value	Notes
Command	Yes		Commands executed in a Telnet session
Host	No	Remote_addr	Host/target to execute the command
Password	Yes		Login Password
Pause	No	1	Pause seconds between each issuing of a command
Port	No	23	Remote port
Prompts	No	[u‘$‘]	List of expected prompts before sending the next command
Timeout	No	30	Remote operation time-out
User	No	Remote_user	Logged in user

Example

• Executing scripts on the remote host

[[email protected] ~]# ansible test -m shell -a "sh test.sh > result chdir=/root"
172.20.21.120 | SUCCESS | rc=0 >>


[[email protected] ~]# ansible test -m shell -a "cat result chdir=/root"
172.20.21.120 | SUCCESS | rc=0 >>
1

Precautions

• If you want to run a command through the shell (for example, you are using, and<>so on|), you must specify a shell in the command, for example/bin/bash -c "/path/to/something | grep else".
• Theresponseskey below is a Python regular expression match, with a prefix for case-insensitive searches?i.
• By default, if you encounter problems more than once, their string responses are repeated. If a continuous problem match requires a different response than a string response, use a list of strings as a response.
• expectModules are designed for simple scenarios, and for more complex requirements, you shouldshellconsiderscriptusing expect code in or modules

Hoxis
Links: https://www.jianshu.com/p/8661c107448d
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Ansible command, Shell, Raw, expect, script, telnet[turn]