trean-url-checker: 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/trean-url-checker - from package: php-horde-trean

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

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