lttng-sessiond: 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/lttng-sessiond - from package: lttng-tools

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

On Debian possible default full paths are:

/usr/bin/lttng-sessiond - from package: lttng-tools

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

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