c99-gcc: 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/c99-gcc - from package: gcc

You may install the required package with command apt-get install {package}
Error in other languages:
c99-gcc: bevel nie gevind nie
c99-gcc: comandă negăsită
c99-gcc: comando não encontrado
c99-gcc: commande introuvable
c99-gcc: command not found
c99-gcc: käsku ei ole
c99-gcc: không tìm thấy lệnh
c99-gcc: komanda nerasta
c99-gcc: Kommando nicht gefunden.
c99-gcc: kommandot finns inte
c99-gcc: komut yok
c99-gcc: nie znaleziono polecenia
c99-gcc: níor aimsíodh an t-ordú
c99-gcc: no se encontró la orden
c99-gcc: no s'ha trobat l'ordre
c99-gcc: opdracht niet gevonden
c99-gcc: parancs nem található
c99-gcc: perintah tidak ditemukan
c99-gcc: príkaz nenájdený
c99-gcc: příkaz nenalezen
c99-gcc: команда не найдена
c99-gcc: командата не е открита
c99-gcc: 命令找不到
c99-gcc: コマンドが見つかりません