pdepend: 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/pdepend - from package: php-pdepend-PHP-Depend

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

On Debian possible default full paths are:

/usr/bin/pdepend - from package: pdepend

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

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