scheme-r5rs.scheme48: 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/scheme-r5rs.scheme48 - from package: scheme48

You may install the required package with command apt-get install {package}
Error in other languages:
scheme-r5rs.scheme48: bevel nie gevind nie
scheme-r5rs.scheme48: comandă negăsită
scheme-r5rs.scheme48: comando não encontrado
scheme-r5rs.scheme48: commande introuvable
scheme-r5rs.scheme48: command not found
scheme-r5rs.scheme48: käsku ei ole
scheme-r5rs.scheme48: không tìm thấy lệnh
scheme-r5rs.scheme48: komanda nerasta
scheme-r5rs.scheme48: Kommando nicht gefunden.
scheme-r5rs.scheme48: kommandot finns inte
scheme-r5rs.scheme48: komut yok
scheme-r5rs.scheme48: nie znaleziono polecenia
scheme-r5rs.scheme48: níor aimsíodh an t-ordú
scheme-r5rs.scheme48: no se encontró la orden
scheme-r5rs.scheme48: no s'ha trobat l'ordre
scheme-r5rs.scheme48: opdracht niet gevonden
scheme-r5rs.scheme48: parancs nem található
scheme-r5rs.scheme48: perintah tidak ditemukan
scheme-r5rs.scheme48: príkaz nenájdený
scheme-r5rs.scheme48: příkaz nenalezen
scheme-r5rs.scheme48: команда не найдена
scheme-r5rs.scheme48: командата не е открита
scheme-r5rs.scheme48: 命令找不到
scheme-r5rs.scheme48: コマンドが見つかりません