dc1394_grab_gray_image: command not found

Have You tried accessing the binary with the full path?

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/dc1394_grab_gray_image - from package: libdc1394-tools

You may install the required package with command yum install {package}
Error in other languages:
dc1394_grab_gray_image: bevel nie gevind nie
dc1394_grab_gray_image: comandă negăsită
dc1394_grab_gray_image: comando não encontrado
dc1394_grab_gray_image: commande introuvable
dc1394_grab_gray_image: command not found
dc1394_grab_gray_image: käsku ei ole
dc1394_grab_gray_image: không tìm thấy lệnh
dc1394_grab_gray_image: komanda nerasta
dc1394_grab_gray_image: Kommando nicht gefunden.
dc1394_grab_gray_image: kommandot finns inte
dc1394_grab_gray_image: komut yok
dc1394_grab_gray_image: nie znaleziono polecenia
dc1394_grab_gray_image: níor aimsíodh an t-ordú
dc1394_grab_gray_image: no se encontró la orden
dc1394_grab_gray_image: no s'ha trobat l'ordre
dc1394_grab_gray_image: opdracht niet gevonden
dc1394_grab_gray_image: parancs nem található
dc1394_grab_gray_image: perintah tidak ditemukan
dc1394_grab_gray_image: príkaz nenájdený
dc1394_grab_gray_image: příkaz nenalezen
dc1394_grab_gray_image: команда не найдена
dc1394_grab_gray_image: командата не е открита
dc1394_grab_gray_image: 命令找不到
dc1394_grab_gray_image: コマンドが見つかりません