prune: 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/prune - from package: graphviz

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

On Debian possible default full paths are:

/usr/bin/prune - from package: graphviz

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

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