ionexit: 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/ionexit - from package: ion

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