pvserver: 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/pvserver - from package: paraview

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

On Debian possible default full paths are:

/usr/bin/pvserver - from package: paraview

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

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