Definition - What does Command-Line Scanner mean?
A command-line scanner is an antivirus or anti-malware scanner that uses the command line instead of a graphical user interface. A well-known open source command-line antivirus is ClamAV. Other anti-malware developers, including Kaspersky and Avira, have command-line based versions available or can call the program from the command line.
Techopedia explains Command-Line Scanner
A command-line scanner is an anti-malware program that is invoked from the command line. These kinds of antivirus programs are normally associated with Unix/Linux systems, but they are also available for Windows and MacOS. One such program is ClamAV.
The advantage of a command-line scanner is its low overhead. Since a command-line program does not have a graphical user interface, it can run faster than a graphical program can. Since antivirus scanning is an intensive operation, it can yield a tangible performance benefit. The other advantage is that such a program can run on a “headless” server without a display. An email server might incorporate antivirus scanning in send and receive operations.