apbs: 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/apbs - from package: apbs

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

On Debian possible default full paths are:

/usr/bin/apbs - from package: apbs

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

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