<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: File Content Sensor

The File Content sensor checks a text file (for example, a log file) for certain strings.

i_round_blueAdditionally, this sensor quotes matching lines in the sensor message.

File Content Sensor

File Content Sensor

i_square_cyanFor a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

Sensor in Other Languages

  • Dutch: Bestands inhoud
  • French: Contenu du fichier
  • German: Datei-Inhalt
  • Japanese: ファイルの内容
  • Portuguese: Conteúdo de arquivo
  • Russian: Содержимое файла
  • Simplified Chinese: 文件内容
  • Spanish: Contenido de archivo


Consider the following remarks and requirements for this sensor:



Performance impact

  • This sensor has a high performance impact. We recommend that you use no more than 200 of this sensor on each probe.

LanmanServer service

  • This sensor requires that the LanmanServer service runs on the target system.

i_round_blueThe display name of the service is Server.

  • To enable the service, log in to the respective system and open the services manager (for example, via services.msc). In the list, find the respective service and set its Start Type to Automatic.

UTF-16 encoded files

Binary files

  • This sensor does not officially support binary files. If you want to monitor them anyway, select Always transmit the entire file in the sensor settings.

Unix line feeds

  • This sensor supports Unix line feeds.


  • This sensor supports IPv6.

Linux system

  • To monitor files on a Linux system, the folder must be accessible via Server Message Block (SMB).


  • Try the fully qualified domain name (FQDN) of the target system if the sensor does not get a connection with the IP address.

Hosted probe

i_podYou cannot add this sensor to the hosted probe of a PRTG Hosted Monitor instance. If you want to use this sensor, add it to a remote probe device.

Basic Sensor Settings

Basic Sensor Settings

Basic Sensor Settings

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

  • filesensor

i_square_cyanFor more information about basic sensor settings, see section Sensor Settings.

Sensor Specific

Sensor Specific

Sensor Specific



File Name

Enter the full path to the file that this sensor monitors. For example, enter C:\Windows\file.txt. to monitor a file on the probe system.

If you use a local path, the sensor only looks for the target file on the probe system, not on the parent device. To monitor a file on the parent device, use the dollar sign ($) like C$\User\username\file.txt.

If the file is located on a network device, use the Universal Naming Convention (UNC) path without the server part (only enter share\folder\file.txt). The sensor inherits the server part (\\server\) from the parent device settings. Enter a valid path and file name.

i_round_redTo monitor Windows shares, the LanmanServer service must run on the target system.

i_round_redTo monitor Linux files, the folder with these files must be accessible via SMB.

i_round_redNote that it might produce a high amount of network traffic if you define that PRTG queries an entire file on your network with every scanning interval.

Search String

Define the string that you want to search the file for. You can enter a simple string in plain text or a regular expression (regex).

i_round_redThe search string must be case-sensitive.

Search Method

Define the method with which you want to provide the search string:

  • Simple string search (default): Search for a simple string in plain text.

i_round_blueThe characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character. You cannot change this behavior. The literal search for these characters is only possible with a regex.

  • Regular expression: Search with a regex.

i_round_redThe pattern must be in one line and only the last matching line is returned.

i_round_bluePRTG supports Perl Compatible Regular Expression (PCRE) regex. For more information, see section Regular Expressions.

File Transmission Handling

Define in which way the sensor transmits the target file to PRTG:

  • Only transmit new lines at the end of the file (default): Send the entire file to PRTG only with the first scanning interval. With the following scanning intervals, the sensor only transmits new lines at the end of the file. It does not send old lines but it still counts them. This option improves the performance of the sensor.
    i_betaThis option is in beta status. Do not expect that it works as expected in every usage scenario.
  • Always transmit the entire file: Send the entire file to PRTG with every scanning interval. If this results in too much traffic on the target system, we recommend that you choose Only transmit new lines at the end of the file (default) instead.

This sensor can only transmit new lines in the following cases:

  • the file is bigger than in the previous scanning interval, and
  • the last line in the file is still in the same place in the file.

i_round_blueThis sensor supports Windows and Linux line endings (CRLF or. LF).

File Encoding

Specify the encoding of the file that this sensor monitors:

  • Windows-1252 (default)
  • UTF-8
  • UTF-16

Sensor Behavior

Define the condition for which the sensor shows the Warning status:

  • Show warning status when the string is not found (default): Show the Warning status if there is no match. Otherwise it remains in the Up status.
  • Show warning status when the string is found: Show the Warning status if there is a match. Otherwise it remains in the Up status.

If Value Changes

Define what the sensor does if the value of the Last Occurrence (Line) channel changes:

  • Ignore (default): Do nothing.
  • Trigger 'change' notification: Send an internal message that indicates a change.
    i_round_blueIn combination with a change trigger, you can use this to trigger a notification if a change occurs.

i_round_redThis sensor does not trigger the notification when the number of Matches changes.

Debug Options

Debug Options

Debug Options



Result Handling

Define what PRTG does with the sensor result:

  • Discard result (default): Do not store the sensor result.
  • Store result: Store the last sensor result in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file names are Result of Sensor [ID].txt and Result of Sensor [ID].Data.txt. This setting is for debugging purposes. PRTG overwrites these files with each scanning interval.

i_round_blueIn a cluster, PRTG stores the result in the PRTG data directory of the master node.

Sensor Display

Sensor Display

Sensor Display



Primary Channel

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

i_round_blueYou can set a different primary channel later by clicking b_channel_primary below a channel gauge on the sensor's Overview tab.

Graph Type

Define how this sensor shows different channels:

  • Show channels independently (default): Show a 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 generates a graph that visualizes the different components of your total traffic.
    i_round_redYou cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you select Stack channels on top of each other above.

Select a unit from the list. PRTG stacks all channels with this unit 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 of these settings are inherited from objects that are higher in the hierarchy. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click b_inherited_enabled under the corresponding setting name to disable the inheritance and to display its options.

i_square_cyanFor more information, see section Inheritance of Settings.

Channel List

i_round_blueWhich channels the sensor actually shows might depend on the target device, the available components, and the sensor setup.




In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status

Last Occurrence (Line)

The line number of the last match

i_round_blueThis channel is the primary channel by default.


The number of matches


i_square_blueKNOWLEDGE BASE

What security features does PRTG include?