orca: 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/orca - from package: orca

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

On Debian possible default full paths are:

/usr/bin/orca - from package: gnome-orca

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

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