dvi2fax: 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/dvi2fax - from package: texlive-dvips

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

On Debian possible default full paths are:

/usr/bin/dvi2fax - from package: texlive-base

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

Error in other languages:
dvi2fax: bevel nie gevind nie
dvi2fax: comandă negăsită
dvi2fax: comando não encontrado
dvi2fax: commande introuvable
dvi2fax: command not found
dvi2fax: käsku ei ole
dvi2fax: không tìm thấy lệnh
dvi2fax: komanda nerasta
dvi2fax: Kommando nicht gefunden.
dvi2fax: kommandot finns inte
dvi2fax: komut yok
dvi2fax: nie znaleziono polecenia
dvi2fax: níor aimsíodh an t-ordú
dvi2fax: no se encontró la orden
dvi2fax: no s'ha trobat l'ordre
dvi2fax: opdracht niet gevonden
dvi2fax: parancs nem található
dvi2fax: perintah tidak ditemukan
dvi2fax: príkaz nenájdený
dvi2fax: příkaz nenalezen
dvi2fax: команда не найдена
dvi2fax: командата не е открита
dvi2fax: 命令找不到
dvi2fax: コマンドが見つかりません