pdfposter: 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 Debian possible default full paths are:

/usr/bin/pdfposter - from package: pdfposter

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

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