pdfbklt: 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 CentOS possible default full paths are:

/usr/bin/pdfbklt - from package: pdf-tools

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/pdfbklt - from package: libtext-pdf-perl

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

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