nhlf77: 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/nhlf77 - from package: ncl-devel

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

On Debian possible default full paths are:

/usr/bin/nhlf77 - from package: libncarg-bin

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

Error in other languages:
nhlf77: bevel nie gevind nie
nhlf77: comandă negăsită
nhlf77: comando não encontrado
nhlf77: commande introuvable
nhlf77: command not found
nhlf77: käsku ei ole
nhlf77: không tìm thấy lệnh
nhlf77: komanda nerasta
nhlf77: Kommando nicht gefunden.
nhlf77: kommandot finns inte
nhlf77: komut yok
nhlf77: nie znaleziono polecenia
nhlf77: níor aimsíodh an t-ordú
nhlf77: no se encontró la orden
nhlf77: no s'ha trobat l'ordre
nhlf77: opdracht niet gevonden
nhlf77: parancs nem található
nhlf77: perintah tidak ditemukan
nhlf77: príkaz nenájdený
nhlf77: příkaz nenalezen
nhlf77: команда не найдена
nhlf77: командата не е открита
nhlf77: 命令找不到
nhlf77: コマンドが見つかりません