firstaidkit-shell: 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/firstaidkit-shell - from package: firstaidkit-engine

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

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