restart-aolserver: 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/share/dotlrn/bin/restart-aolserver - from package: dotlrn
/usr/share/openacs/bin/restart-aolserver - from package: openacs

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

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