expand: 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/expand - from package: coreutils

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

On Debian possible default full paths are:

/usr/bin/expand - from package: coreutils

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

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