gcaps: 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/gcaps - from package: ncl

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

On Debian possible default full paths are:

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

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

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