skymon: 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/skymon - from package: mon

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

On Debian possible default full paths are:

/usr/bin/skymon - from package: mon

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

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