dpkg-maintscript-helper: command not found

Have You tried accessing the binary with the full path?

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/dpkg-maintscript-helper - from package: dpkg

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

On Debian possible default full paths are:

/usr/bin/dpkg-maintscript-helper - from package: dpkg

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