scalebar: 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/scalebar - from package: mapserver

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

On Debian possible default full paths are:

/usr/bin/scalebar - from package: mapserver-bin

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

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