pdfdetach: 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/pdfdetach - from package: xpdf

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

On Debian possible default full paths are:

/usr/bin/pdfdetach - from package: poppler-utils

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

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