v4l-info: 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/v4l-info - from package: xawtv

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

On Debian possible default full paths are:

/usr/bin/v4l-info - from package: v4l-conf

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

Error in other languages:
v4l-info: bevel nie gevind nie
v4l-info: comandă negăsită
v4l-info: comando não encontrado
v4l-info: commande introuvable
v4l-info: command not found
v4l-info: käsku ei ole
v4l-info: không tìm thấy lệnh
v4l-info: komanda nerasta
v4l-info: Kommando nicht gefunden.
v4l-info: kommandot finns inte
v4l-info: komut yok
v4l-info: nie znaleziono polecenia
v4l-info: níor aimsíodh an t-ordú
v4l-info: no se encontró la orden
v4l-info: no s'ha trobat l'ordre
v4l-info: opdracht niet gevonden
v4l-info: parancs nem található
v4l-info: perintah tidak ditemukan
v4l-info: príkaz nenájdený
v4l-info: příkaz nenalezen
v4l-info: команда не найдена
v4l-info: командата не е открита
v4l-info: 命令找不到
v4l-info: コマンドが見つかりません