csg_density: 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 Debian possible default full paths are:

/usr/bin/csg_density - from package: votca-csg

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