monshow: 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/monshow - from package: mon

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

On Debian possible default full paths are:

/usr/bin/monshow - from package: mon

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

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