pamsharpness: 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/pamsharpness - from package: netpbm-progs

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

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