rosstack: 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/rosstack - from package: rospack

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

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