db2x_texixml: 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/db2x_texixml - from package: docbook2X

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

On Debian possible default full paths are:

/usr/bin/db2x_texixml - from package: docbook2X

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

Error in other languages:
db2x_texixml: bevel nie gevind nie
db2x_texixml: comandă negăsită
db2x_texixml: comando não encontrado
db2x_texixml: commande introuvable
db2x_texixml: command not found
db2x_texixml: käsku ei ole
db2x_texixml: không tìm thấy lệnh
db2x_texixml: komanda nerasta
db2x_texixml: Kommando nicht gefunden.
db2x_texixml: kommandot finns inte
db2x_texixml: komut yok
db2x_texixml: nie znaleziono polecenia
db2x_texixml: níor aimsíodh an t-ordú
db2x_texixml: no se encontró la orden
db2x_texixml: no s'ha trobat l'ordre
db2x_texixml: opdracht niet gevonden
db2x_texixml: parancs nem található
db2x_texixml: perintah tidak ditemukan
db2x_texixml: príkaz nenájdený
db2x_texixml: příkaz nenalezen
db2x_texixml: команда не найдена
db2x_texixml: командата не е открита
db2x_texixml: 命令找不到
db2x_texixml: コマンドが見つかりません