pnmrotate: 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/pnmrotate - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pnmrotate - from package: netpbm

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

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