changepagestring: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/changepagestring - from package: libcam-pdf-perl

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