pat: 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 Debian possible default full paths are:

/usr/bin/pat - from package: dist

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

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