elpa2_print_kernels: 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/lib64/mpich/bin/elpa2_print_kernels - from package: elpa-mpich
/usr/lib/mpich/bin/elpa2_print_kernels - from package: elpa-mpich
/usr/lib64/openmpi/bin/elpa2_print_kernels - from package: elpa-openmpi
/usr/lib/openmpi/bin/elpa2_print_kernels - from package: elpa-openmpi

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

Error in other languages:
elpa2_print_kernels: bevel nie gevind nie
elpa2_print_kernels: comandă negăsită
elpa2_print_kernels: comando não encontrado
elpa2_print_kernels: commande introuvable
elpa2_print_kernels: command not found
elpa2_print_kernels: käsku ei ole
elpa2_print_kernels: không tìm thấy lệnh
elpa2_print_kernels: komanda nerasta
elpa2_print_kernels: Kommando nicht gefunden.
elpa2_print_kernels: kommandot finns inte
elpa2_print_kernels: komut yok
elpa2_print_kernels: nie znaleziono polecenia
elpa2_print_kernels: níor aimsíodh an t-ordú
elpa2_print_kernels: no se encontró la orden
elpa2_print_kernels: no s'ha trobat l'ordre
elpa2_print_kernels: opdracht niet gevonden
elpa2_print_kernels: parancs nem található
elpa2_print_kernels: perintah tidak ditemukan
elpa2_print_kernels: príkaz nenájdený
elpa2_print_kernels: příkaz nenalezen
elpa2_print_kernels: команда не найдена
elpa2_print_kernels: командата не е открита
elpa2_print_kernels: 命令找不到
elpa2_print_kernels: コマンドが見つかりません