nc4tonc3: 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 CentOS possible default full paths are:

/usr/bin/nc4tonc3 - from package: netcdf4-python

You may install the required package with command yum install {package}

Error in other languages:
nc4tonc3: bevel nie gevind nie
nc4tonc3: comandă negăsită
nc4tonc3: comando não encontrado
nc4tonc3: commande introuvable
nc4tonc3: command not found
nc4tonc3: käsku ei ole
nc4tonc3: không tìm thấy lệnh
nc4tonc3: komanda nerasta
nc4tonc3: Kommando nicht gefunden.
nc4tonc3: kommandot finns inte
nc4tonc3: komut yok
nc4tonc3: nie znaleziono polecenia
nc4tonc3: níor aimsíodh an t-ordú
nc4tonc3: no se encontró la orden
nc4tonc3: no s'ha trobat l'ordre
nc4tonc3: opdracht niet gevonden
nc4tonc3: parancs nem található
nc4tonc3: perintah tidak ditemukan
nc4tonc3: príkaz nenájdený
nc4tonc3: příkaz nenalezen
nc4tonc3: команда не найдена
nc4tonc3: командата не е открита
nc4tonc3: 命令找不到
nc4tonc3: コマンドが見つかりません