pkfix-helper: 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/pkfix-helper - from package: texlive-extra-utils

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

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