check-trac-subtickets: 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/bin/check-trac-subtickets - from package: trac-subtickets

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

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