openapp: 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/openapp - from package: gnustep-make

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

On Debian possible default full paths are:

/usr/bin/openapp - from package: gnustep-common

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

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