linuxdcpp: 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/linuxdcpp - from package: linuxdcpp

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

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