https://www.clamav.net/

Packages are available for Linux, MacOS and Windows

ClamAV can be updated offline or online

Offline DB update:

http://database.clamav.net/daily.cvd
http://database.clamav.net/main.cvd
http://database.clamav.net/bytecode.cvd

A Linux package install will probably go in /usr, with:

applications in /usr/bin
daemons in /usr/sbin
libraries in /usr/lib
headers in /usr/include
configs in /etc/clamav
databases in /var/lib/clamav

The full list of packages includes:

clamav - command-line interface
clamav-base - base package
clamav-daemon - scanner daemon
clamav-docs - documentation
clamav-freshclam - virus database update utility
clamav-milter - sendmail integration
clamdscan - A command-line client for clamd similar to clamscan
clamav-testfiles - test files
libclamav-dev - development files
libclamav9 - library
libclamunrar9 - unrar support

For Redhat like distribution, you'll find it in EPEL repo

EPEL offers a selection of packages to install ClamAV:

  clamd - The Clam AntiVirus Daemon
  clamav - End-user tools for the Clam Antivirus scanner
  clamav-data - Virus signature data for the Clam Antivirus scanner
  clamav-devel - Header files and libraries for the Clam Antivirus scanner
  clamav-lib - Dynamic libraries for the Clam Antivirus scanner
  clamav-milter - Milter module for the Clam Antivirus scanner
  clamav-update - Auto-updater for the Clam Antivirus scanner data-files

Most users will only need to run:

dnf install -y clamav clamd clamav-update

Run these to generate example configs in /etc/clamav/, if needed:

clamconf -g freshclam.conf > freshclam.conf
clamconf -g clamd.conf > clamd.conf
clamconf -g clamav-milter.conf > clamav-milter.conf

To allow ClamAV to operate under SELinux, run the following:

setsebool -P antivirus_can_scan_system 1