tz_convert: 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/tz_convert - from package: orage

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

On Debian possible default full paths are:

/usr/bin/tz_convert - from package: orage

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

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