zxpdf: 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/zxpdf - from package: xpdf

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

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