sqlmetal: 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/sqlmetal - from package: mono-data

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

On Debian possible default full paths are:

/usr/bin/sqlmetal - from package: mono-devel

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

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