obgrep: 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/obgrep - from package: openbabel

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

On Debian possible default full paths are:

/usr/bin/obgrep - from package: openbabel

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

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