cvs-upgrade: 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/cvs-upgrade - from package: cvs-buildpackage

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

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