snexpire: 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

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/sbin/snexpire - from package: sn

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