db2pdf: 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/db2pdf - from package: docbook-utils-pdf

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

On Debian possible default full paths are:

/usr/bin/db2pdf - from package: docbook-utils

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

Error in other languages:
db2pdf: bevel nie gevind nie
db2pdf: comandă negăsită
db2pdf: comando não encontrado
db2pdf: commande introuvable
db2pdf: command not found
db2pdf: käsku ei ole
db2pdf: không tìm thấy lệnh
db2pdf: komanda nerasta
db2pdf: Kommando nicht gefunden.
db2pdf: kommandot finns inte
db2pdf: komut yok
db2pdf: nie znaleziono polecenia
db2pdf: níor aimsíodh an t-ordú
db2pdf: no se encontró la orden
db2pdf: no s'ha trobat l'ordre
db2pdf: opdracht niet gevonden
db2pdf: parancs nem található
db2pdf: perintah tidak ditemukan
db2pdf: príkaz nenájdený
db2pdf: příkaz nenalezen
db2pdf: команда не найдена
db2pdf: командата не е открита
db2pdf: 命令找不到
db2pdf: コマンドが見つかりません