zftp: 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 CentOS possible default full paths are:

/usr/bin/zftp - from package: cernlib-packlib

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/zftp - from package: zftp

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

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