pessulus: 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/pessulus - from package: pessulus

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

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