pbs_sched: 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/sbin/pbs_sched - from package: torque-scheduler

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

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