pss: 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/pss - from package: pss

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

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