cgm2ncgm: 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/cgm2ncgm - from package: ncl

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

On Debian possible default full paths are:

/usr/bin/cgm2ncgm - from package: ncl-ncarg

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

Error in other languages:
cgm2ncgm: bevel nie gevind nie
cgm2ncgm: comandă negăsită
cgm2ncgm: comando não encontrado
cgm2ncgm: commande introuvable
cgm2ncgm: command not found
cgm2ncgm: käsku ei ole
cgm2ncgm: không tìm thấy lệnh
cgm2ncgm: komanda nerasta
cgm2ncgm: Kommando nicht gefunden.
cgm2ncgm: kommandot finns inte
cgm2ncgm: komut yok
cgm2ncgm: nie znaleziono polecenia
cgm2ncgm: níor aimsíodh an t-ordú
cgm2ncgm: no se encontró la orden
cgm2ncgm: no s'ha trobat l'ordre
cgm2ncgm: opdracht niet gevonden
cgm2ncgm: parancs nem található
cgm2ncgm: perintah tidak ditemukan
cgm2ncgm: príkaz nenájdený
cgm2ncgm: příkaz nenalezen
cgm2ncgm: команда не найдена
cgm2ncgm: командата не е открита
cgm2ncgm: 命令找不到
cgm2ncgm: コマンドが見つかりません