ionstart: command not found

Have You tried accessing the binary with the full path?

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/ionstart - from package: ion

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