digitemp_DS2490: 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/digitemp_DS2490 - from package: digitemp

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

On Debian possible default full paths are:

/usr/bin/digitemp_DS2490 - from package: digitemp

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

Error in other languages:
digitemp_DS2490: bevel nie gevind nie
digitemp_DS2490: comandă negăsită
digitemp_DS2490: comando não encontrado
digitemp_DS2490: commande introuvable
digitemp_DS2490: command not found
digitemp_DS2490: käsku ei ole
digitemp_DS2490: không tìm thấy lệnh
digitemp_DS2490: komanda nerasta
digitemp_DS2490: Kommando nicht gefunden.
digitemp_DS2490: kommandot finns inte
digitemp_DS2490: komut yok
digitemp_DS2490: nie znaleziono polecenia
digitemp_DS2490: níor aimsíodh an t-ordú
digitemp_DS2490: no se encontró la orden
digitemp_DS2490: no s'ha trobat l'ordre
digitemp_DS2490: opdracht niet gevonden
digitemp_DS2490: parancs nem található
digitemp_DS2490: perintah tidak ditemukan
digitemp_DS2490: príkaz nenájdený
digitemp_DS2490: příkaz nenalezen
digitemp_DS2490: команда не найдена
digitemp_DS2490: командата не е открита
digitemp_DS2490: 命令找不到
digitemp_DS2490: コマンドが見つかりません