PRTG Manual: SSH Script Sensor

The SSH Script sensor connects to a Linux/Unix system via Secure Shell (SSH) and executes a script file located on the target system. The sensor shows the execution time, and can show one value returned by the executable file or script (in one channel only). For details about the return value format please see the Application Programming Interface (API) Definition.

Note: For security reasons, the script file must be stored on the target system. Please make sure the script has executable rights.

For this sensor type credentials for Linux (SSH/WBEM) systems must be defined for the device you want to use the sensor on.

Note: Not all Linux/Unix and Mac OS distributions can be supported by this sensor type.

For a general introduction to SSH monitoring, please see Monitoring via SSH section.

Add Sensor

The Add Sensor dialog appears when adding a new sensor on a device manually. It only shows the setting fields that are imperative for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change all settings in the sensor's Settings tab later.

The following settings for this sensor differ in the 'Add Sensor' dialog in comparison to the sensor's settings page:

Sensor Settings


Select a script file from the list. The drop down menu will list all script files available in the /var/prtg/scripts directory on the target Linux/Unix system. In order for the files to appear in this list, please store them into this directory. Please make sure the script has executable rights. In order for the sensor to show the expected values and sensor status, your files must use the right format for the returned values (in this case, exitcode:value:message to stdout). The exitcode will determine the sensor status. For detailed information on the expected return format and on how to build custom sensors, please see the API documentation (Application Programming Interface (API) Definition). There, find detailed information the the "Custom Sensors" tab. For an example script, please see More section below.

Value Type

Define what kind of values your script file gives back. Choose between:

  • Integer: An integer is expected as return value. If the script gives back a float, PRTG will display the value 0.
  • Float: A float is expected as return value, with a dot (.) between pre-decimal position and decimal places. In this setting, the sensor will also display integer values unless they don't produce a buffer overflow.
  • Counter: Your script returns an integer which increases. PRTG will  show the difference between the values of two sensor scans. Note: A counter must return an integer; float is not supported here!

Sensor Settings

On the sensor's details page, click on the Settings tab to change settings.

Note: If not set explicitly in a sensor's settings, it will connect to the IP Address or DNS Name defined in the settings of the parent device the sensor is created on.

Basic Sensor Settings

Sensor Name

Enter a meaningful name to identify the sensor. The name will be shown by default in the device tree and in all alarms.


Enter one or more tags, separated by space or comma. You can use tags to group sensors and use tag-filtered views later on. Tags are not case sensitive. We recommend using the default value. You can add additional tags to it, if you like. Other tags are automatically inherited from objects further up in the device tree. Those are not visible here.


Select a priority for the sensor. This setting determines where the sensor will be placed in sensor lists. Top priority will be at the top of a list. You can choose from one star (low priority) to five stars (top priority).

Sensor Settings


Shows the script that is executed with each sensor scan, as defined on sensor creation. Once a sensor is created this value cannot be changed. It is shown for reference purposes only. If you need to change this, please add the sensor anew.


If your script file catches command line parameters, you can define them here. Placeholders can be used as well. For a full list of all placeholders please see the API documentation (Application Programming Interface (API) Definition). Note: Please make sure you write the placeholders in quotes to ensure that they are working properly if their values contain blanks. Use single quotation marks ' ' with PowerShell scripts, and double quotes " " with all others. Please enter a string or leave the field empty.

Mutex Name

Define any desired mutex name for the process. All EXE/Script sensors having the same mutex name will be executed serially (not simultaneously). This is useful if you use a lot of sensors and want to avoid high resource usage caused by processes running simultaneously. For links to more information, please see the More section below. Please enter a string or leave the field empty.

Value Type

Shows the expected value type, chosen on sensor creation. Once a sensor is created this value cannot be changed. It is shown for reference purposes only. If you need to change this, please add the sensor anew. Note: The sensor cannot handle string values.

If Value Changes

Define what shall be done in case the value of this sensor changes. You can choose between:

  • Ignore changes (default): No action will be taken on change.
  • Trigger 'On Change' notification: The sensor will send an internal message indicating that its value has changed. In combination with a Change Trigger, you can use this mechanism to trigger a notification whenever the sensor value changes.

SSH Specific

Connection Timeout (sec.)

Define a timeout for the connection. This is the the time the sensor waits to establish a connection to the host. You should keep this value as low as possible.

Shell Timeout (sec.)

Define a timeout for the shell response. This is the time in seconds the sensor waits for the shell to return a response after it has sent its specific command (e.g. cat /proc/loadavg).

SSH Port

Define which port this sensor will use for the SSH connection. Choose between:

  • Inherit port number from parent device (default): Use the port number as defined in the Credentials for Linux/Solaris/Mac OS (SSH/WBEM) Systems section of the device this sensor is created on.
  • Enter custom port number: Do not use the port number from the parent device's settings, but define a different port number below.

Use Port Number

This field is only visible if the custom port number setting is enabled above. Enter the port number this sensor will use for the SSH connection. Please enter an integer value.

Result Handling

Define what will be done with the result of the query. Choose between:

  • Discard text result: Do not store the requested web page.
  • Store latest text result: Store the last result received from the query to the "Logs (System)" directory (on the Master node, if in a cluster). File name: Result of Sensor [ID].txt. This is for debugging purposes. The file will be overridden with each scanning interval. For information on how to find the folder used for storage, please see Data Storage section.

Sensor Display

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel will always be displayed underneath the sensor's name. The available options depend on what channels are available for this sensor.

Chart Type

Define how different channels will be shown for this sensor.

  • Show channels independently (default): Show an own graph for each channel.
  • Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This will generate an easy-to-read graph which visualizes the different components of your total traffic. Note: This option cannot be used in combination with manual Vertical Axis Scaling (available in the Sensor Channels Settings settings).

Stack Unit

This setting is only available if stacked graphs are selected above. Choose a unit from the list. All channels with this unit will be stacked on top of each other. By default, you cannot exclude single channels from stacking, if they use the selected unit. However, there is an advanced procedure to do so.

Inherited Settings

By default, all following settings are inherited from objects higher in the hierarchy and should be changed there, if necessary. Often, best practice is to change them centrally in the Root group's settings. To change a setting for this object, disable inheritance by clicking on the check mark symbol in front of the respective setting name. You will then see the options described below.

Scanning Interval

Scanning Interval

The scanning interval determines the time the sensor waits between two scans. Select a scanning interval (seconds, minutes, or hours) from the list. You can change the available intervals in the system administration.

Schedules, Dependencies, and Maintenance Window

Note: Inheritance for schedules, dependencies, and maintenance windows cannot be interrupted; the according settings from the parent objects will always be active. However, you can define additional settings here. They will be active in parallel to the parent objects' settings.


Select a schedule from the list. Schedules can be used to pause monitoring for a certain time span (days, hours) throughout the week. You can create new schedules and edit existing ones in the account settings. Note: Schedules are generally inherited. New schedules will be added to existing ones, so all schedules are active.

Maintenance Window

Specify if you want to set-up a one-time maintenance window. During a maintenance window this object and all child objects will not be monitored. They will enter a paused state then. Choose between:

  • Not set (monitor continuously): No maintenance window will be set.
  • Set up a one-time maintenance window: Pause monitoring within a maintenance window.

Maintenance Begins At

This field is only visible if maintenance window is enabled above. Use the date time picker to enter the start date and time of the maintenance window.

Maintenance End At

This field is only visible if maintenance window is enabled above. Use the date time picker to enter the end date and time of the maintenance window.

Dependency Type

Define a dependency type. Dependencies can be used to pause monitoring for an object depending on the status of another. You can choose between:

  • Use parent: Pause the current sensor if the device it is created on is in a Down status, or if it is paused by another dependency.
  • Select object: Pause the current sensor if the device it is created on is in an Down status, or if it is paused by another dependency. Additionally, pause the current sensor if a specific other object in the device tree is in a Down status, or if it is paused by another dependency. Select below.
  • Master object for parent: Make this sensor the master object for its parent device. The sensor will influence the behavior of the device it is created on: If the sensor is in a Down status, the device will be paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor will be paused if the parent group of its parent device is in a Down status, or if it is paused by another dependency.

Note: Testing your dependencies is easy! Simply choose Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later all dependent objects should be paused.


This field is only visible if the select object option is enabled above. Click on the reading-glass symbol and use the object selector to choose an object on which the current sensor will be dependent on.

Delay (Seconds)

Define a time span. After the master object for this dependency comes back to an Up status, monitoring of the depending objects will be additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Please enter an integer value in seconds. Note: This setting is not available if you choose this sensor to be the Master object for parent. In this case, please define delays in the parent Device Settings or the superior Group Settings.

Access Rights

User Group Access

Define which user group(s) will have access to the object you're editing. A table with user groups and right is shown; it contains all user groups from your setup. For each user group you can choose from the following access rights:

  • Inherited: Use the settings of the parent object.
  • None: Users in this group cannot see or edit the object. The object does not show up in lists and in the device tree. Exception: If a child object is visible to the user, the object is visible in the device tree, though not accessible.
  • Read: Users in this group can see the object and review its monitoring results.
  • Write: Users in this group can see the object, review its monitoring results, and edit the object's settings. They cannot edit access rights settings.
  • Full: Users in this group can see the object, review its monitoring results, edit the object's settings, and edit access rights settings.

You can create new user groups in the System Administration—User Groups settings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option.

Channel Unit Configuration

Channel Unit Types

For each type of sensor channel, define the unit in which data is displayed. If defined on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):

  • Bandwidth
  • Memory
  • Disk
  • File
  • Custom

Note: Custom channel types can be set on sensor level only.


Knowledge Base: Is there a shell script example for PRTG's SSH Script Sensor?

Information about custom scripts and executables

Knowledge Base: What is the Mutex Name in PRTG's EXE/Script Sensor's settings?

Knowledge Base: How and Where Does PRTG Store its Data?

Knowledge Base: How can I test if parameters are correctly transmitted to my script when using an EXE/Script sensor?


Click on the Channels tab to change display settings, spike filter, and limits. For detailed information, please see Sensor Channels Settings section.


Click on the Notifications tab to change notification triggers. For detailed information, please see Sensor Notifications Settings section.


For more general information about settings, please see Object Settings section.

Sensor Settings Overview

For information about sensor settings, please see the following sections: