bibtexconv: 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/bibtexconv - from package: bibtexconv

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

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