nvi: 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/nvi - from package: nvi

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

On Debian possible default full paths are:

/usr/bin/nvi - from package: nvi

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

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