dtach: 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/dtach - from package: dtach

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

On Debian possible default full paths are:

/usr/bin/dtach - from package: dtach

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

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