# 2 Remote commands

#### Overview

With remote commands you can define that a certain pre-defined command
is automatically executed on the monitored host upon some condition.

Thus remote commands are a powerful mechanism for smart pro-active
monitoring.

In the most obvious uses of the feature you can try to:

-   Automatically restart some application (web server, middleware, CRM)
    if it does not respond
-   Use IPMI 'reboot' command to reboot some remote server if it does
    not answer requests
-   Automatically free disk space (removing older files, cleaning /tmp)
    if running out of disk space
-   Migrate a VM from one physical box to another depending on the CPU
    load
-   Add new nodes to a cloud environment upon insufficient CPU (disk,
    memory, whatever) resources

Configuring an action for remote commands is similar to that for sending
a message, the only difference being that Zabbix will execute a command
instead of sending a message.

::: noteimportant
Remote commands are not supported to be executed
on Zabbix agents monitored by Zabbix proxy, so for commands from Zabbix
server to agent a direct connection is required.
:::

Remote commands are limited to 255 characters. Multiple commands can be
executed one after another by placing them on a new line. Remote
commands may contain macros. See also the [command
execution](/manual/appendix/command_execution) page.

Remote commands are executed even if the target host is in maintenance.

The following tutorial provides step-by-step instructions on how to set
up remote commands.

#### Configuration

Those remote commands that are executed on Zabbix agent (custom scripts)
must be first enabled in the respective
[zabbix\_agentd.conf](/manual/appendix/config/zabbix_agentd).

Make sure that the **EnableRemoteCommands** parameter is set to **1**
and uncommented. Restart agent daemon if changing this parameter.

::: noteimportant
Remote commands do not work with active Zabbix
agents.
:::

Then, when configuring a new action in *Configuration→Actions*:

-   In the *Operations* tab, select the **Remote command** operation
    type
-   Select the remote command type (IPMI, Custom script, SSH, Telnet,
    Global script)
-   Enter the remote command

For example:

    sudo /etc/init.d/apache restart 

In this case, Zabbix will try to restart an Apache process. With this
command, make sure that the command is executed on Zabbix agent (mark
the respective radio button against *Execute on*).

::: noteimportant
Note the use of **sudo** - Zabbix user does not
have permissions to restart system services by default. See below for
hints on how to configure **sudo**.
:::

::: noteclassic
Zabbix agent should run on the remote host and accept
incoming connections. Zabbix agent executes commands in
background.
:::

::: noteimportant
Zabbix does not check if a command has been
executed successfully.
:::

Remote commands on Zabbix agent are executed without timeout by the
system.run\[,nowait\] key. On Zabbix server remote commands are executed
with timeout as set in the TrapperTimeout parameter of
zabbix\_server.conf file.

-   In the *Conditions* tab, define the appropriate conditions. In this
    example, set that the action is activated upon any disaster problems
    with one of Apache applications.

![](../../../../../../assets/en/manual/config/conditions_restart.png)

#### Access permissions

Make sure that the 'zabbix' user has execute permissions for configured
commands. One may be interested in using **sudo** to give access to
privileged commands. To configure access, execute as root:

    # visudo

Example lines that could be used in *sudoers* file:

    # allows 'zabbix' user to run all commands without password.
    zabbix ALL=NOPASSWD: ALL

    # allows 'zabbix' user to restart apache without password.
    zabbix ALL=NOPASSWD: /etc/init.d/apache restart

::: notetip
On some systems *sudoers* file will prevent non-local
users from executing commands. To change this, comment out
**requiretty** option in */etc/sudoers*.
:::

#### Remote commands with multiple interfaces

If the target system has multiple interfaces of the selected type
(Zabbix agent or IPMI), remote commands will be executed on the default
interface.

#### IPMI remote commands

For IPMI remote commands the following syntax should be used:

    <command> [<value>]

where

-   <command> - one of IPMI commands without spaces
-   <value> - 'on', 'off' or any unsigned integer. <value>
    is an optional parameter.

#### Examples

##### Example 1

Restart of Windows on certain condition.

In order to automatically restart Windows upon a problem detected by
Zabbix, define the following actions:

|PARAMETER|Description|
|---------|-----------|
|Operation type|'Remote command'|
|Type|'Custom script'|
|Command|c:\\windows\\system32\\shutdown.exe -r -f|

##### Example 2

Restart the host by using IPMI control.

|PARAMETER|Description|
|---------|-----------|
|Operation type|'Remote command'|
|Type|'IPMI'|
|Command|reset|

##### Example 3

Power off the host by using IPMI control.

|PARAMETER|Description|
|---------|-----------|
|Operation type|'Remote command'|
|Type|'IPMI'|
|Command|power off|