"Scan archive for viruses" command
This command is accessible both in file management and in archive management modes. It unpacks one or several archives to temporary folder and checks contents of this folder with a third party virus scanner, which must be installed on a user's computer. In the archive management mode it processes only the currently opened archive, in the file management mode all archives found in selected files and folders will be processed.
Dialog displayed by this command contains the following fields.
List of antivirus software installed on a computer and identified by WinRAR. If this list contains several virus scanners, you may choose anyone which you like. If the list contains only "User defined" item, it means that WinRAR could not find any antivirus software and you need to specify a scanner name and parameters manually.
Name of virus scanner executable. You need to modify this field only if WinRAR cannot find antivirus software installed on your computer and "Virus scanners found by WinRAR" list contains only "User defined" item. In such case you need to press "Browse" button and locate a virus scanner .exe file, which will be called by WinRAR to check unpacked files.
Parameters passed to virus scanner. You need to modify this field either if WinRAR cannot find antivirus software installed on your computer or if it passes invalid parameters to virus scanner. For example, it may happen if command line syntax of antivirus program is changed in a new version. Usually virus scanners require only one parameter - the name of folder containing unpacked files. WinRAR denotes this folder as %f. Since its name may include spaces, it is necessary to enclose it in quotes, so most likely you need to place "%f" string to this field. Though, some scanners may require additional options, which can be found in their documentation.
If you use only one antivirus and do not need to modify its parameters every time, you may skip the virus scanner selection dialog by turning "Propose to select virus scanner" option in Security settings off.