y4mshift: 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 Debian possible default full paths are:

/usr/lib/mjpegtools/bin/y4mshift - from package: mjpegtools

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

Error in other languages:
y4mshift: bevel nie gevind nie
y4mshift: comandă negăsită
y4mshift: comando não encontrado
y4mshift: commande introuvable
y4mshift: command not found
y4mshift: käsku ei ole
y4mshift: không tìm thấy lệnh
y4mshift: komanda nerasta
y4mshift: Kommando nicht gefunden.
y4mshift: kommandot finns inte
y4mshift: komut yok
y4mshift: nie znaleziono polecenia
y4mshift: níor aimsíodh an t-ordú
y4mshift: no se encontró la orden
y4mshift: no s'ha trobat l'ordre
y4mshift: opdracht niet gevonden
y4mshift: parancs nem található
y4mshift: perintah tidak ditemukan
y4mshift: príkaz nenájdený
y4mshift: příkaz nenalezen
y4mshift: команда не найдена
y4mshift: командата не е открита
y4mshift: 命令找不到
y4mshift: コマンドが見つかりません