I installed it with Yast, but it does not appear in menu,
so, at shell,
what to type to run it ?

Hello,

clamav is to be run in a console with the 'clamscan' commando. If you want to upgrade the virus definition, you have to run a 'freshclam'.
You will find more info with the man clamscan.

There is a GUI for KDE call 'klamav'.
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free_ouyo

how to update clamav?

Clam AntiVirus: freshclam 0.87
(C) 2002 - 2005 ClamAV Team - http://www.clamav.net/team.html

--help -h show help
--version -V print version number and exit
--verbose -v be verbose
--debug enable debug messages
--quiet only output error messages
--stdout write to stdout instead of stderr

--config-file=FILE read configuration from FILE.
--log=FILE -l FILE log into FILE
--daemon -d run in daemon mode
--foreground -f run daemon in foreground
--pid=FILE -p FILE save daemon's pid in FILE
--user=USER -u USER run as USER
--no-dns force old non-DNS verification method
--checks=#n -c #n number of checks per day, 1 <= n <= 50
--datadir=DIRECTORY download new databases into DIRECTORY
--daemon-notify[=/path/clamd.conf] send RELOAD command to clamd
--local-address=IP -a IP bind to IP for HTTP downloads
--on-update-execute=COMMAND execute COMMAND after successful update
--on-error-execute=COMMAND execute COMMAND if errors occured
--on-outdated-execute=COMMAND execute COMMAND when software is outdated

when i try to update, a main.cvd file was downloaded, what can i do with it?

Hello,

If you run a 'freshclam', the files 'main.cvd' and 'daily.cvd' are checked and updated so normally, you don't have to take other actions to upgrade the database.

If you want to run clamav, you have to run from terminal the commando 'clamscan' with some options. A display of the options is given with 'clamscan --help'.

You can choose to show only infected files (-i). A verbose output is available with the -v and a recursive scan is obtained with the -r.
A log file of the infected file can be specified with the -l ....

The best is to create a little script to update the virusdb and a other one to scan the disk with the owner desired options.
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free_ouyo

ok, thanks, BTW, do you think linux is prone to virus infection? I feel that linux does not need antivirus lie windows.

I think Linux does not have such virus problem like windows but you can meet problems with rootkits and you can also use a linux virus-scanner to scan a windows computer or partition.
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free_ouyo