sge_shepherd: 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/sge_shepherd - from package: gridengine-execd
/usr/share/gridengine/bin/lx26-amd64/sge_shepherd - from package: gridengine-execd

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

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