obprop: 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/obprop - from package: openbabel

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

On Debian possible default full paths are:

/usr/bin/obprop - from package: openbabel

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

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