ceph: 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/ceph - from package: ceph-common

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

On Debian possible default full paths are:

/usr/bin/ceph - from package: ceph-common

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

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