ncmpc: 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/ncmpc - from package: ncmpc

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

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