zwrite: 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/zwrite - from package: zephyr-clients

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

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