mtn-cleanup: 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/mtn-cleanup - from package: monotone

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

On Debian possible default full paths are:

/usr/bin/mtn-cleanup - from package: monotone-extras

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

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