vlmerge: 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 Debian possible default full paths are:

/usr/bin/vlmerge - from package: libvcs-lite-perl

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

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