gnucap: 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/gnucap - from package: gnucap

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

On Debian possible default full paths are:

/usr/bin/gnucap - from package: gnucap

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

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