lxappearance: 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/lxappearance - from package: lxappearance

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

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