regina-config: 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/regina-config - from package: libregina3-dev

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