fastaq_to_random_subset: command not found

Have You tried accessing the binary with the full path?

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/fastaq_to_random_subset - from package: fastaq

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