wiipdf: 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/wiipdf - from package: wiipdf

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

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