which-pkg-broke: 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/which-pkg-broke - from package: debian-goodies

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

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