gcmd-block: 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 Debian possible default full paths are:

/usr/bin/gcmd-block - from package: gnome-commander

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

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