In Ansible, ad-hoc commands are one-liners you run directly in the terminal to perform quick tasks on your managed nodes — without writing a full playbook.

🧪 Syntax of an Ad-Hoc Command:

ansible <host-pattern> -m <module-name> -a "<module-options>"

🔹 Components:

• ansible: the CLI tool.

• <host-pattern>: inventory group or host (all, webservers, 192.168.1.10).

• -m <module-name>: specify which module to use.

• -a "<args>": module arguments in quotes.

  Let's master Ansible ad-hoc commands where i have grouped the modules by phases.

  🔰 PHASE 1: System Basics, File Management

  1. ping – Test connectivity

  2. command – Run system commands

  3. shell – Run shell commands with pipes, variables, redirection

  4. reboot – Reboot systems

  5. setup – Gather system facts

  6. cron – Similar to an alarm

  7. copy – Copy local files to remote

  8. file – Create/delete files/dirs, manage permissions

     • Create file:

     • Create directory:

     • Delete file:

  9. stat – Check if a file exists

---

🧑 PHASE 2: Others

1. user – Create/remove users

2. yum (RedHat/CentOS)

3. apt (Debian/Ubuntu)

4. package (Generic across OSes)

5. service – Start/stop/restart services

---

🔰 PHASE 1: System Basics, File Management

✅ ping Module – Purpose

• Tests whether the target hosts are reachable and can execute Ansible modules (i.e., Python must be installed).

• Does not use ICMP like Linux ping; it sends a "ping" message over SSH using Python.

If Python is not installed:

Use raw module instead:

    ansible all -m raw -a "apt install -y python3"

📌 Basic Syntax

    ansible <host-pattern> -m ping

---

🔧 Examples

1. Ping all hosts in inventory:

    ansible all -m ping

2. Ping a specific host:

    ansible webserver -m ping

3. Ping using a custom inventory file:

    ansible all -i /path/to/inventory -m ping

4. Ping with verbose output:

    ansible all -m ping -v

Explanation:

• -v = verbose mode. It shows extra details about what's happening behind the scenes during the ping.

• You can use more v’s for deeper detail:

  • -v: basic details

  • -vv: connection/debug logs

  • -vvv: Ansible internal debugging

  • -vvvv: full SSH communication

🧪 Output:

With -v, you’ll see extra info like:

    Using /etc/ansible/hosts as inventory file
    <192.168.1.10> ESTABLISH SSH CONNECTION
    ...
    192.168.1.10 | SUCCESS => {
        "changed": false,
        "ping": "pong"
    }

Useful for debugging inventory issues or SSH problems.

🧪 Expected Output:

    192.168.1.10 | SUCCESS => {
        "changed": false,
        "ping": "pong"
    }

This confirms:

• Host is reachable via SSH

• Python is installed and working

✅ That's all for the ping module.

✅ command Module – Purpose

• Used to run simple system commands on remote hosts.

• It is Default module so no need to use -m for this module commands.

• Does NOT support shell features like |, >, &&, variables like $HOME.

---

📌 Syntax

ansible <host-pattern> -a "<command>"  # default is command module

---

🔧 Examples

1. Run uptime on all hosts:

ansible all -a "uptime"

2. List files in /tmp:

ansible all -a "ls -l /tmp"

3. Display current user:

ansible all -a "whoami"

4. Use with specific user:

ansible all -a "hostname" -u raj

---

❌ What It Can't Do:

• No shell features like:

    ansible all -a "cat file.txt | grep error"     # ❌ will fail
    ansible all -a "echo $HOME"                    # ❌ will not expand
  

• For these, use the shell module instead.

---

🧪 Sample Output

192.168.1.10 | SUCCESS | rc=0 >>
 14:02:30 up 10 days,  2 users,  load average: 0.15, 0.10, 0.05

✅ shell Module – Purpose

• Runs shell commands on remote hosts.

• Supports features that command module does not:

  • Pipes (|)

  • Redirection (>, >>)

  • Logical operators (&&, ||)

  • Environment variables ($HOME, $PATH)

  • Bash-specific syntax

---

📌 Syntax

ansible <host-pattern> -m shell -a "<shell-command>"

---

🔧 Examples

1. Use environment variable:

ansible all -m shell -a "echo $HOME"

2. Use pipe (|) to filter:

ansible all -m shell -a "cat /etc/passwd | grep root"

3. Redirect command output to a file:

ansible all -m shell -a "date > /tmp/current_date.txt"

4. Run multiple commands:

ansible all -m shell -a "mkdir /tmp/demo && touch /tmp/demo/file.txt"

5. Run a script on remote:

ansible all -m shell -a "bash /opt/scripts/cleanup.sh"

6. Append text to a file:

ansible all -m shell -a "echo 'Welcome Raj' >> /tmp/welcome.txt"

---

🧪 Sample Output

192.168.1.10 | SUCCESS | rc=0 >>
/home/raj

---

⚠️ Best Practices

⚔️ Tricky and Real-World Shell Ad-Hoc Examples

---

🔹 1. Check if a file exists, and create it only if missing

ansible all -m shell -a "test -f /tmp/demo.txt || touch /tmp/demo.txt"

🧠 Explanation:

• test -f: checks if the file exists

• || touch: runs touch only if file is missing

---

🔹 2. Append hostname and timestamp to a log file

ansible all -m shell -a "echo \"$(hostname) - $(date)\" >> /tmp/host_log.txt"

🧠 Useful for tracking which host did what and when.

---

🔹 3. Run a multi-line command using a heredoc

ansible all -m shell -a "cat <<EOF > /tmp/script.sh
#!/bin/bash
echo Hello Raj
date
EOF"

🧠 This creates a script file /tmp/script.sh with multiple lines in one go.

---

🔹 4. Delete all .log files older than 7 days

ansible all -m shell -a "find /var/log -name '*.log' -mtime +7 -exec rm -f {} \;"

🧠 This is a common log rotation/cleanup task.

---

🔹 5. Search and count a word in a file

ansible all -m shell -a "grep -o 'error' /var/log/syslog | wc -l"

🧠 Find how many times error occurred in syslog.

---

🔹 6. Check if a port is listening (e.g., 22)

ansible all -m shell -a "ss -tuln | grep ':22'"

🧠 Verifies if SSH is actively listening.

---

🔹 7. Add a cron job via shell

ansible all -m shell -a "(crontab -l ; echo '0 1 * * * /usr/bin/uptime') | crontab -"

🧠 Appends a new cron job without deleting old ones.

✅ reboot Module – Purpose

• Gracefully reboots target machines.

• Waits for them to come back online.

• Handles SSH reconnects, timeouts, and safe delays.

• Works better than shell "reboot" or command "reboot" which break SSH and cause task failures.

---

📌 Syntax

ansible <host-pattern> -m reboot

---

🔧 Basic Examples

1. Reboot all hosts safely:

ansible all -m reboot

---

2. Reboot with a custom reboot timeout (e.g., 300 seconds):

ansible all -m reboot -a "reboot_timeout=300"

---

3. Reboot with a delay of 60 seconds before starting:

ansible all -m reboot -a "pre_reboot_delay=60"

---

4. Reboot and wait for specific port (e.g., SSH port 22):

ansible all -m reboot -a "test_command='ss -tuln | grep :22'"

---

5. Reboot with both pre-delay and post-delay:

ansible all -m reboot -a "pre_reboot_delay=10 post_reboot_delay=30"

⚠️ Notes

---

🧪 Sample Output

192.168.1.10 | SUCCESS => {
    "changed": true,
    "elapsed": 44
}

This means the system rebooted and was reachable again in 44 seconds.

✅ setup Module – Purpose

• Gathers facts (detailed system info) from remote hosts:

  • IP address, hostname, OS, memory, CPU, disk, network interfaces, etc.

• These facts are useful in:

  • Ad-hoc analysis

  • Conditional logic in playbooks

  • Dynamic inventories

---

📌 Basic Syntax

ansible <host-pattern> -m setup

---

🔧 Useful Examples

1. Get all system facts from all hosts:

ansible all -m setup

🧠 Outputs a large JSON with hundreds of values.

---

2. Get facts for a specific host:

ansible web1 -m setup

---

3. Filter facts using a fact subset (like network, hardware, etc.):

ansible all -m setup -a "filter=ansible_processor"

✅ Shows only CPU info.

ansible all -m setup -a "filter=ansible_hostname"

✅ Shows only hostname.

ansible all -m setup -a "filter=ansible_all_ipv4_addresses"

✅ Shows all IP addresses.

---

4. Filter facts using a keyword pattern:

ansible all -m setup -a "filter=ansible_*_mb"

✅ Matches facts like memory size (e.g., ansible_memtotal_mb, ansible_memfree_mb)

---

📦 Commonly Used Fact Names

---

🧪 Sample Output

"ansible_facts": {
  "ansible_hostname": "raj-ubuntu",
  "ansible_memtotal_mb": 8096,
  "ansible_processor_cores": 4,
  "ansible_all_ipv4_addresses": ["192.168.1.10"]
}

---

🕒 cron Module

✅ Purpose:

• Manage cron jobs on remote machines.

---

📌 Syntax (create job):

ansible all -m cron -a "name='<job-name>' minute=0 hour=2 job='/path/to/command'"

---

🔧 Examples:

1. Add a cron job to run backup at 2 AM daily:

ansible all -m cron -a "name='daily-backup' minute=0 hour=2 job='/usr/local/bin/backup.sh'"

2. Remove the above cron job:

ansible all -m cron -a "name='daily-backup' state=absent"

3. Create a job that runs every 15 minutes:

ansible all -m cron -a "name='check-disk' minute=*/15 job='df -h >> /tmp/disk.log'"

4. Disable a cron job without deleting it:

ansible all -m cron -a "name='check-disk' job='df -h >> /tmp/disk.log' disabled=yes"

---

🧪 Verify cron entries:

ansible all -a "crontab -l"

📁 copy Module – Copy Files to Remote Hosts

✅ Purpose:

• Copies files or inline content from the control node (your system) to remote hosts.

---

📌 Basic Syntax:

ansible all -m copy -a "src=/path/to/source dest=/path/to/destination"

---

🔧 Common Examples:

1. Copy a local file to /tmp on remote host:

ansible all -m copy -a "src=./hello.txt dest=/tmp/hello.txt"

2. Overwrite and set permissions:

ansible all -m copy -a "src=./config.conf dest=/etc/myapp/config.conf mode=0644 owner=root group=root"

3. Send inline content as a file:

ansible all -m copy -a "content='Raj was here!' dest=/tmp/note.txt"

4. Force overwrite (default is true):

ansible all -m copy -a "src=./motd dest=/etc/motd force=yes"

---

⚠️ Notes:

• The src path is local to control node, not remote.

• Use force=no to avoid overwriting files.

---

🧱 file Module – Manage File/Directory Attributes

✅ Purpose:

• Creates files, directories, symlinks.

• Changes ownership, permissions.

• Deletes files/directories.

---

📌 Basic Syntax:

ansible all -m file -a "path=/path/to/file state=<state> [other-options]"

---

🔧 Common Examples:

1. Create a directory:

ansible all -m file -a "path=/opt/demo state=directory mode=0755"

2. Create an empty file:

ansible all -m file -a "path=/tmp/empty.txt state=touch"

3. Delete a file or directory:

ansible all -m file -a "path=/tmp/oldfile.txt state=absent"
ansible all -m file -a "path=/opt/demo state=absent"

4. Change ownership of a file:

ansible all -m file -a "path=/tmp/test.sh owner=raj group=raj mode=0755"

📂 stat Module – Purpose

• Checks file or directory existence and metadata like:

  • exists (True/False)

  • size

  • mode (permissions)

  • mtime, ctime, atime

  • uid, gid, owner, group

  • isdir, islink, etc.

---

📌 Syntax:

ansible all -m stat -a "path=/path/to/file_or_dir"

---

🔧 Examples:

1. Check if file exists:

ansible all -m stat -a "path=/etc/passwd"

🔍 Output contains:

"exists": true,
"isreg": true,
"mode": "0644",
"size": 2397

---

2. Check if directory exists:

ansible all -m stat -a "path=/var/log"

🔍 Look for:

• "isdir": true

• "exists": true

---

3. Check file permissions and ownership:

ansible all -m stat -a "path=/etc/hosts"

🔍 Useful for auditing:

"owner": "root",
"group": "root",
"mode": "0644"

---

🧠 When to Use stat?

Use it when you want to conditionally act based on:

• File existence

• Type (file vs dir)

• Permissions

---

🧑 PHASE 2: Others

👤 user Module – Purpose

Used to create, modify, or delete user accounts on remote systems.

---

📌 Syntax:

ansible all -m user -a "name=<username> [options]"

---

🔧 Common Examples:

1. ✅ Create a user:

ansible all -m user -a "name=raj"

➡️ Creates user raj with default settings.

2. ❌ Remove a user:

ansible all -m user -a "name=demo state=absent"

➡️ Deletes the user, but keeps home directory by default.

3. Check User Existence:

ansible all -a "id raj"

---

🔧 service Module – Purpose

• Start, stop, restart, reload, enable, or disable services on remote hosts.

---

📌 Syntax:

ansible all -m service -a "name=<service-name> state=<state> [enabled=yes|no]"

---

🔧 Common Examples:

1. ✅ Start a service (e.g., nginx)

ansible all -m service -a "name=nginx state=started"

---

2. ✅ Stop a service

ansible all -m service -a "name=nginx state=stopped"

---

3. 🔁 Restart a service

ansible all -m service -a "name=nginx state=restarted"

---

4. 🔄 Reload service configuration

ansible all -m service -a "name=nginx state=reloaded"

---

5. 🚀 Enable service to start on boot

ansible all -m service -a "name=nginx enabled=yes"

---

6. ❌ Disable auto-start on boot

ansible all -m service -a "name=nginx enabled=no"

---

🧠 Notes:

---

🧪 Check status of a service:

ansible all -a "systemctl status nginx"

📦 apt Module (Debian, Ubuntu)

✅ Syntax:

ansible all -m apt -a "name=<package-name> state=<present|absent|latest> update_cache=yes"

---

🔧 Examples:

1. ✅ Install a package (e.g., nginx)

ansible all -m apt -a "name=nginx state=present update_cache=yes"

2. ❌ Remove a package

ansible all -m apt -a "name=nginx state=absent"

3. 🔄 Update an existing package to latest version

ansible all -m apt -a "name=nginx state=latest"

4. 🧠 Run full system upgrade

ansible all -m apt -a "upgrade=dist update_cache=yes"

---

🍔 yum Module (RHEL, CentOS, Fedora)

✅ Syntax:

ansible all -m yum -a "name=<package-name> state=<present|absent|latest>"

---

🔧 Examples:

1. ✅ Install a package

ansible all -m yum -a "name=httpd state=present"

2. ❌ Remove a package

ansible all -m yum -a "name=httpd state=absent"

3. 🔄 Update to latest version

ansible all -m yum -a "name=httpd state=latest"

4. 🧠 Update all packages (full system update)

ansible all -m yum -a "name='*' state=latest"

---

🧪 Check package is installed:

ansible all -a "dpkg -l | grep nginx"     # Debian
ansible all -a "rpm -qa | grep httpd"     # RHEL

📦 package Module – Purpose

• Universal package manager wrapper.

• Works across:

  • apt (Debian/Ubuntu)

  • yum / dnf (RHEL, CentOS, Fedora)

  • zypper (SUSE)

  • pkg (FreeBSD)

• The package module uses the default package manager of the host OS.

• For advanced options (like update_cache, upgrade, repo handling), use apt, yum directly.

---

📌 Basic Syntax:

ansible all -m package -a "name=<package-name> state=<present|absent|latest>"

---

🔧 Common Examples

✅ 1. Install a package (e.g., curl)

ansible all -m package -a "name=curl state=present"

---

🔁 2. Update package to the latest version

ansible all -m package -a "name=curl state=latest"

---

❌ 3. Remove a package

ansible all -m package -a "name=curl state=absent"

---

✅ 4. Install multiple packages

ansible all -m package -a "name=['htop','curl','git'] state=present"

---

🧠 Why Use package Instead of apt or yum?

---

🧪 Check if package installed (command module):

ansible all -a "which curl"

---

WE MADE IT !!

⚠️ Note

• All the modules covered in this blog come under ansible.builtin collection. To explore more modules under this collection, visit https://docs.ansible.com/ansible/latest/collections/ansible/builtin/index.html#plugins-in-ansible-builtin

• Also to cover other collections, visit https://docs.ansible.com/ansible/latest/collections/index.html