viewvc-standalone: 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 Debian possible default full paths are:

/usr/bin/viewvc-standalone - from package: viewvc

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

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