webtidy: 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/webtidy - from package: perl-HTML-Tidy

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

On Debian possible default full paths are:

/usr/bin/webtidy - from package: libhtml-tidy-perl

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

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