circos: 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
/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/circos - from package: circos

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