install-packages: 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/share/diskimage-builder/elements/dpkg/bin/install-packages - from package: diskimage-builder
/usr/share/diskimage-builder/elements/opensuse/bin/install-packages - from package: diskimage-builder
/usr/share/diskimage-builder/elements/yum/bin/install-packages - from package: diskimage-builder

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

On Debian possible default full paths are:

/usr/share/diskimage-builder/elements/dpkg/bin/install-packages - from package: python-diskimage-builder
/usr/share/diskimage-builder/elements/opensuse/bin/install-packages - from package: python-diskimage-builder
/usr/share/diskimage-builder/elements/yum/bin/install-packages - from package: python-diskimage-builder

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

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