mussh: 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/mussh - from package: mussh

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

On Debian possible default full paths are:

/usr/bin/mussh - from package: mussh

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

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