cx18-ctl: 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/cx18-ctl - from package: v4l-utils

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

On Debian possible default full paths are:

/usr/bin/cx18-ctl - from package: v4l-utils

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

Error in other languages:
cx18-ctl: bevel nie gevind nie
cx18-ctl: comandă negăsită
cx18-ctl: comando não encontrado
cx18-ctl: commande introuvable
cx18-ctl: command not found
cx18-ctl: käsku ei ole
cx18-ctl: không tìm thấy lệnh
cx18-ctl: komanda nerasta
cx18-ctl: Kommando nicht gefunden.
cx18-ctl: kommandot finns inte
cx18-ctl: komut yok
cx18-ctl: nie znaleziono polecenia
cx18-ctl: níor aimsíodh an t-ordú
cx18-ctl: no se encontró la orden
cx18-ctl: no s'ha trobat l'ordre
cx18-ctl: opdracht niet gevonden
cx18-ctl: parancs nem található
cx18-ctl: perintah tidak ditemukan
cx18-ctl: príkaz nenájdený
cx18-ctl: příkaz nenalezen
cx18-ctl: команда не найдена
cx18-ctl: командата не е открита
cx18-ctl: 命令找不到
cx18-ctl: コマンドが見つかりません