msgcache: 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 Debian possible default full paths are:

/usr/lib/xymon/client/bin/msgcache - from package: xymon-client

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

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