cross-gcc-gensource: 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

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/cross-gcc-gensource - from package: cross-gcc-dev

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