feh-cam: 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/bin/feh-cam - from package: feh

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

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