sdcc-sdnm: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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 CentOS possible default full paths are:

/usr/bin/sdcc-sdnm - from package: sdcc

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