Introduction in one sentence: Ad-hoc commands are Ansible’s “quick knife”, allowing you to manage servers in bulk with a single command in the command line.
1. What are Ad-hoc Commands?
In Ansible, there are two main execution methods:
1.Ad-hoc commands: Execute a single task directly in the command line, suitable for temporary bulk operations.
2.Playbook: Automation scripts written in YAML files, suitable for complex, multi-step tasks.
Characteristics of Ad-hoc commands:
·Fast
·One-time
·No need to write scripts
Common scenarios:
·Test server connectivity
·Bulk install software
·Bulk modify file permissions
·Bulk restart services
2. Ad-hoc Command Syntax
ansible<host group> -m <module name> -a “<module parameters>”[options]
Common options:
|
Option |
Function |
|
-m |
Specify module name (default is command module) |
|
-a |
Pass module parameters |
|
-k |
Interactive input of SSH password (recommended to configure passwordless login) |
|
-b |
Execute with sudo privileges (equivalent to root permissions) |
|
–check |
Dry run mode, does not actually execute |
|
–limit |
Limit the range of hosts to execute |
3. Detailed Explanation of Common Modules
1. ping — Test connectivity
ansible all -m ping
Returns pong indicating the connection is normal.
2. command — Execute command (without using Shell)
ansible all -m command -a“uptime”
Cannot use Shell features (such as pipes, redirection).
3. shell — Execute Shell command
ansible all -m shell -a“cat /etc/os-release | grep PRETTY_NAME”
Supports Shell features such as pipes and variables.
4. copy — Copy files to managed nodes
ansible webservers -m copy -a“src=./index.html dest=/var/www/html/index.html owner=nginx group=nginx mode=0644”
·src: Source file path on the control node
·dest: Target path on the managed node
·owner/group/mode: File permission settings
5. file — Manage files and directories
ansible webservers -m file -a“path=/var/www/html state=directory mode=0755”
·Create directory
ansible webservers -m file -a“path=/tmp/test.txt state=touch”
·Delete file
ansible webservers -m file -a“path=/tmp/test.txt state=absent”
6. yum/apt — Install and uninstall software packages
·CentOS / RHEL：
ansible webservers -m yum -a“name=nginx state=present”
·Ubuntu / Debian：
ansible webservers -m apt -a“name=nginx state=present update_cache=yes”
Common state:
·present：Install
·absent：Uninstall
·latest：Install the latest version
7. service — Manage services
ansible webservers -m service -a“name=nginx state=started enabled=yes”
·started：Start
·stopped：Stop
·restarted：Restart
·enabled：Enable on boot
8. user — Manage users
ansible all -m user -a“name=dev password={{ ‘123456’ | password_hash(‘sha512’) }} state=present”
It is recommended to manage passwords with vars and not write them in plain text in the command.
4. Practical Ad-hoc Examples
1. Batch view disk space
ansible all -m shell -a“df -h”
2. Batch update packages
ansible all -m yum -a“name=* state=latest”
3. Batch synchronize time
ansible all -m shell -a“ntpdate ntp.aliyun.com”
5. Common Issues and Troubleshooting
1.SSH connection failed
oConfirm if passwordless login is configured successfully
oCheck if /etc/ansible/hosts is configured correctly
oIf the port is not 22, add -e ansible_port=xxx
2.Insufficient permissions
oAdd -b to use sudo privileges
oConfirm that the managed node’s sudo configuration allows passwordless execution
3.Command execution result garbled
oUnify the LANG encoding on the control node and managed node, for example:
exportLANG=en_US.UTF-8
6. Summary and Next Article Preview
In this article, we learned:
·Using Ad-hoc commands to quickly execute tasks in bulk
·How to use common modules
·Practical batch management examples
The next article “Introduction to Playbooks and Basics of YAML” will take us into Ansible’s core capability—writing repeatable automation tasks with Playbooks, truly achieving “write once, run multiple times”.
💡 Tip: In actual production, temporary operations can use Ad-hoc, but repetitive operations are recommended to be written as Playbooks for easier maintenance and version management.
