rebuild-security-providers: 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/sbin/rebuild-security-providers - from package: libgcj-common

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

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