What is a log file?

Posted by on 9. September 2018

A log file, also referred to as a log file, is a file in which computer processes log various events. Log files are important sources of information to make the processes on a system traceable. They can be used, for example, for problem analysis or the reconstruction of lost data.

The log file, often also called log file or log file, is a file in which events are logged on computer systems or in networks. They are a useful tool for documenting or archiving the many different processes in a comprehensible way. Log files can be used, for example, as a source of information for error analysis when a system crashes or for investigating user behavior. It is often possible to reconstruct lost data with the help of log files. Logfiles are automatically created, filled and continuously stored on the system. Logfiles are often used in the web environment to investigate access to web pages and to obtain information about visitors to web pages.

Further typical application areas for log files are transaction logging in databases, event logs of operating systems or the logging of network events on a network computer. The evaluation of log files is called log file analysis. If you are looking for a VPN provider make sure they don`t store log files, http://www.VPNnologs.com/ has a list of these.

In which areas are log files generated?

Many different processes of common operating systems such as Windows, MacOS or Linux continuously generate log files on the computer unnoticed by the user. Examples of this are the system logbook of Linux or the event display of Windows. Among other things, user logins, process events or error messages from software and hardware are recorded in these log files.

Other programs that generate log files are e-mail servers, firewalls, virus scanners or installation routines. Web servers or FTP servers also continuously store log files in which user information and data accesses are logged.

Purpose and use of the log files

A log file can serve different purposes. Log files are usually used for the following actions:

  1. Problem analysis of computer systems (investigation of a computer crash)
  2. Problem analysis in networks
  3. Traceability of data transactions
  4. Reconstruction of lost data
  5. Investigation of data accesses
  6. Investigation of user behaviour
  7. Logging of safety-relevant events
  8. Fulfillment of compliance requirements

In the web environment, search engine optimization (SEO) often relies on log files. The stored data provide clues about the origin of visitors and the pages visited on a website. This information can be used to optimize the website with regard to user friendliness and information content. Further information that can be obtained from the log files of a web server is performance data of the website, accessibility information and error data.

Structure, content and information elements of a log file

As a rule, log files have a line-oriented structure. Each event fills a line of the log file and begins or ends with the time and date (time stamp) of the entry. Since log files are continuously updated, the entries are usually sorted chronologically. The newest entry is at the top of the list, the oldest entry is at the bottom. Many recording processes limit the maximum number of entries in order to prevent the size of log files from increasing arbitrarily. If the maximum size is reached, the oldest entries are overwritten. Another important information that is often found in every line of a log file is a rating of the importance of the recorded event.

This subdivision makes it easier to search log files for relevant information. Common categories for the importance of events are:

  • Debug or Trace: Information about the program flow
  • Information: Information about normal transactions of a process
  • Warning: Important information about transactions that can lead to errors or security-related events.
  • Error: Application or process errors that have occurred
  • Critical or fatal error: an error that occurs that causes a process to crash or terminate.

In addition to time stamps and the importance of events, the following information is often found in log files:

  • Name of the event that occurred with any additional information.
  • Status of the system at the event
  • executed command
  • affected user of the event
  • IP addresses of users or associated processes
  • affected files and file paths
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