html2ps: 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/html2ps - from package: html2ps

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

On Debian possible default full paths are:

/usr/bin/html2ps - from package: html2ps

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

Error in other languages:
html2ps: bevel nie gevind nie
html2ps: comandă negăsită
html2ps: comando não encontrado
html2ps: commande introuvable
html2ps: command not found
html2ps: käsku ei ole
html2ps: không tìm thấy lệnh
html2ps: komanda nerasta
html2ps: Kommando nicht gefunden.
html2ps: kommandot finns inte
html2ps: komut yok
html2ps: nie znaleziono polecenia
html2ps: níor aimsíodh an t-ordú
html2ps: no se encontró la orden
html2ps: no s'ha trobat l'ordre
html2ps: opdracht niet gevonden
html2ps: parancs nem található
html2ps: perintah tidak ditemukan
html2ps: príkaz nenájdený
html2ps: příkaz nenalezen
html2ps: команда не найдена
html2ps: командата не е открита
html2ps: 命令找不到
html2ps: コマンドが見つかりません