palmtopnm: 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
/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/palmtopnm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/palmtopnm - from package: netpbm

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