tclsh: 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/tclsh - from package: tcl

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

On Debian possible default full paths are:

/usr/bin/tclsh - from package: tcl

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

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