add_rel_link.sh: 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/lib/ace/bin/add_rel_link.sh - from package: libace-dev

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

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