cache-mgr: 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

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/cache-mgr - from package: sra-toolkit

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