gvfs-monitor-dir: 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/gvfs-monitor-dir - from package: gvfs

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

On Debian possible default full paths are:

/usr/bin/gvfs-monitor-dir - from package: gvfs-bin

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

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