chipmunk_demos: 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/chipmunk_demos - from package: chipmunk-dev

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

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