mount.cifs: 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:

/sbin/mount.cifs - from package: cifs-utils

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

On Debian possible default full paths are:

/sbin/mount.cifs - from package: cifs-utils

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

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