sb: 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/sb - from package: lrzsz

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

On Debian possible default full paths are:

/usr/bin/sb - from package: lrzsz

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

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