approx-gc: 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/sbin/approx-gc - from package: approx

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

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