watchgnupg: 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/watchgnupg - from package: gnupg2

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

On Debian possible default full paths are:

/usr/bin/watchgnupg - from package: gnupg2

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

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