connman-ui-gtk: 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/connman-ui-gtk - from package: connman-ui

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