tshark: 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/sbin/tshark - from package: wireshark

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

On Debian possible default full paths are:

/usr/bin/tshark - from package: tshark

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

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