ps-watcher: command not found

Have You tried accessing the binary with the full path?

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/bin/ps-watcher - from package: ps-watcher

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