clamdscan: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/clamdscan - from package: clamd

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/clamdscan - from package: clamdscan

You may install the required package with command apt-get install {package}

Error in other languages:
clamdscan: bevel nie gevind nie
clamdscan: comandă negăsită
clamdscan: comando não encontrado
clamdscan: commande introuvable
clamdscan: command not found
clamdscan: käsku ei ole
clamdscan: không tìm thấy lệnh
clamdscan: komanda nerasta
clamdscan: Kommando nicht gefunden.
clamdscan: kommandot finns inte
clamdscan: komut yok
clamdscan: nie znaleziono polecenia
clamdscan: níor aimsíodh an t-ordú
clamdscan: no se encontró la orden
clamdscan: no s'ha trobat l'ordre
clamdscan: opdracht niet gevonden
clamdscan: parancs nem található
clamdscan: perintah tidak ditemukan
clamdscan: príkaz nenájdený
clamdscan: příkaz nenalezen
clamdscan: команда не найдена
clamdscan: командата не е открита
clamdscan: 命令找不到
clamdscan: コマンドが見つかりません