login: 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 CentOS possible default full paths are:

/usr/lib/heimdal/bin/login - from package: heimdal-appl-clients
/usr/share/rear/skel/default/bin/login - from package: rear
/bin/login - from package: util-linux-ng

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

On Debian possible default full paths are:

/bin/login - from package: login

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