horde-run-task: 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 CentOS possible default full paths are:

/usr/bin/horde-run-task - from package: php-horde-horde

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/horde-run-task - from package: php-horde

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

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