ncftpls: 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/ncftpls - from package: ncftp

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

On Debian possible default full paths are:

/usr/bin/ncftpls - from package: ncftp

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

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