pgmtofs: 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/pgmtofs - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pgmtofs - from package: netpbm

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

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