s2cdecl: 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/s2cdecl - from package: scheme2c

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

Error in other languages:
s2cdecl: bevel nie gevind nie
s2cdecl: comandă negăsită
s2cdecl: comando não encontrado
s2cdecl: commande introuvable
s2cdecl: command not found
s2cdecl: käsku ei ole
s2cdecl: không tìm thấy lệnh
s2cdecl: komanda nerasta
s2cdecl: Kommando nicht gefunden.
s2cdecl: kommandot finns inte
s2cdecl: komut yok
s2cdecl: nie znaleziono polecenia
s2cdecl: níor aimsíodh an t-ordú
s2cdecl: no se encontró la orden
s2cdecl: no s'ha trobat l'ordre
s2cdecl: opdracht niet gevonden
s2cdecl: parancs nem található
s2cdecl: perintah tidak ditemukan
s2cdecl: príkaz nenájdený
s2cdecl: příkaz nenalezen
s2cdecl: команда не найдена
s2cdecl: командата не е открита
s2cdecl: 命令找不到
s2cdecl: コマンドが見つかりません