pdfbook: 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/pdfbook - from package: pdfjam

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

On Debian possible default full paths are:

/usr/bin/pdfbook - from package: texlive-extra-utils

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

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