cgnsconvert: 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/cgnsconvert - from package: cgns-convert

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

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