nlogin: 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/lib/rancid/bin/nlogin - from package: rancid

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