expect_passmass: 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

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/expect_passmass - from package: expect

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