dash: 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:

/bin/dash - from package: dash

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

On Debian possible default full paths are:

/bin/dash - from package: dash

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

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