dpkg-checkdeps: 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 Debian possible default full paths are:

/usr/bin/dpkg-checkdeps - from package: ruby-debian

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

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