polarssl_pk_sign: 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/polarssl_pk_sign - from package: libpolarssl-runtime

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