trimhistory: 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/server/bin/trimhistory - from package: xymon

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

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