gvfs-ls: 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 CentOS possible default full paths are:

/usr/bin/gvfs-ls - from package: gvfs

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

On Debian possible default full paths are:

/usr/bin/gvfs-ls - from package: gvfs-bin

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