preg: 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/preg - from package: emboss

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

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