cdecl: 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/cdecl - from package: cdecl
/usr/bin/cdecl - from package: cutils

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

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