ionadmin: 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/ionadmin - from package: ion

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

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