clamdtop: 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/clamdtop - from package: clamd

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

On Debian possible default full paths are:

/usr/bin/clamdtop - from package: clamav-daemon

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

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