dviconcat: 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/dviconcat - from package: texlive-dviutils

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

On Debian possible default full paths are:

/usr/bin/dviconcat - from package: texlive-binaries

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

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