filterlinks: 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/share/circos/tools/filterlinks/bin/filterlinks - from package: circos-tools

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

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