mpi_kmeans: 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/bin/mpi_kmeans - from package: mpikmeans-tools

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

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