mapcache_seed: 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/mapcache_seed - from package: mapcache-tools

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

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