flexbar: command not found

Have You tried accessing the binary with the full path?

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 Debian possible default full paths are:

/usr/bin/flexbar - from package: flexbar

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