pbmtog3: 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/pbmtog3 - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pbmtog3 - from package: netpbm

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

Error in other languages:
pbmtog3: bevel nie gevind nie
pbmtog3: comandă negăsită
pbmtog3: comando não encontrado
pbmtog3: commande introuvable
pbmtog3: command not found
pbmtog3: käsku ei ole
pbmtog3: không tìm thấy lệnh
pbmtog3: komanda nerasta
pbmtog3: Kommando nicht gefunden.
pbmtog3: kommandot finns inte
pbmtog3: komut yok
pbmtog3: nie znaleziono polecenia
pbmtog3: níor aimsíodh an t-ordú
pbmtog3: no se encontró la orden
pbmtog3: no s'ha trobat l'ordre
pbmtog3: opdracht niet gevonden
pbmtog3: parancs nem található
pbmtog3: perintah tidak ditemukan
pbmtog3: príkaz nenájdený
pbmtog3: příkaz nenalezen
pbmtog3: команда не найдена
pbmtog3: командата не е открита
pbmtog3: 命令找不到
pbmtog3: コマンドが見つかりません