spider.sh: 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

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/share/doc/librrd-simple-perl/examples/rrd-server/bin/spider.sh - from package: librrd-simple-perl

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