pluginviewer: 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/sbin/pluginviewer - from package: cyrus-sasl

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

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