c++decl: 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/c++decl - from package: cdecl

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

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