17.3. Viewing Log Files

⁠17.3. Viewing Log Files

Most log files are in plain text format. You can view them with any text editor such as Vi or Emacs. Some log files are readable by all users on the system; however, root privileges are required to read most log files.

To view system log files in an interactive, real-time application, use the Log File Viewer.

Installing the gnome-system-log package

In order to use the Log File Viewer, first ensure the gnome-system-log package is installed on your system by running, as root:

yum install gnome-system-log

For more information on installing packages with Yum, refer to Section 5.2.4, “Installing Packages”.

After you have installed the gnome-system-log package, you can open the Log File Viewer by selecting Applications → System Tools → Log File Viewer from the Activities menu, or type the following command at a shell prompt:

gnome-system-log

The application only displays log files that exist; thus, the list might differ from the one shown in Figure 17.1, “ Log File Viewer ”.

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Figure 17.1. Log File Viewer

The Log File Viewer application lets you filter any existing log file. Click on Filters from the menu and select Manage Filters to define or edit your desired filter.

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Figure 17.2. Log File Viewer — filters

Adding or editing a filter lets you define its parameters as is shown in Figure 17.3, “ Log File Viewer — defining a filter ”.

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Figure 17.3. Log File Viewer — defining a filter

When defining a filter, you can edit the following parameters:

Name — Specifies the name of the filter.
Regular Expression — Specifies the regular expression that will be applied to the log file and will attempt to match any possible strings of text in it.
Effect
- Highlight — If checked, the found results will be highlighted with the selected color. You may select whether to highlight the background or the foreground of the text.
- Hide — If checked, the found results will be hidden from the log file you are viewing.

When you have at least one filter defined, you may select it from the Filters menu and it will automatically search for the strings you have defined in the filter and highlight/hide every successful match in the log file you are currently viewing.

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Figure 17.4. Log File Viewer — enabling a filter

When you check the Show matches only option, only the matched strings will be shown in the log file you are currently viewing.