pkcs11_listcerts: 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 CentOS possible default full paths are:

/usr/bin/pkcs11_listcerts - from package: pam_pkcs11

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/pkcs11_listcerts - from package: libpam-pkcs11

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

Error in other languages:
pkcs11_listcerts: bevel nie gevind nie
pkcs11_listcerts: comandă negăsită
pkcs11_listcerts: comando não encontrado
pkcs11_listcerts: commande introuvable
pkcs11_listcerts: command not found
pkcs11_listcerts: käsku ei ole
pkcs11_listcerts: không tìm thấy lệnh
pkcs11_listcerts: komanda nerasta
pkcs11_listcerts: Kommando nicht gefunden.
pkcs11_listcerts: kommandot finns inte
pkcs11_listcerts: komut yok
pkcs11_listcerts: nie znaleziono polecenia
pkcs11_listcerts: níor aimsíodh an t-ordú
pkcs11_listcerts: no se encontró la orden
pkcs11_listcerts: no s'ha trobat l'ordre
pkcs11_listcerts: opdracht niet gevonden
pkcs11_listcerts: parancs nem található
pkcs11_listcerts: perintah tidak ditemukan
pkcs11_listcerts: príkaz nenájdený
pkcs11_listcerts: příkaz nenalezen
pkcs11_listcerts: команда не найдена
pkcs11_listcerts: командата не е открита
pkcs11_listcerts: 命令找不到
pkcs11_listcerts: コマンドが見つかりません