opensc-explorer: 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/opensc-explorer - from package: opensc

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

On Debian possible default full paths are:

/usr/bin/opensc-explorer - from package: opensc

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

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