memcapable: 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 CentOS possible default full paths are:

/usr/bin/memcapable - from package: libmemcached10

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