pbm2g3: 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/pbm2g3 - from package: mgetty-sendfax

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

On Debian possible default full paths are:

/usr/bin/pbm2g3 - from package: mgetty-fax

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

Error in other languages:
pbm2g3: bevel nie gevind nie
pbm2g3: comandă negăsită
pbm2g3: comando não encontrado
pbm2g3: commande introuvable
pbm2g3: command not found
pbm2g3: käsku ei ole
pbm2g3: không tìm thấy lệnh
pbm2g3: komanda nerasta
pbm2g3: Kommando nicht gefunden.
pbm2g3: kommandot finns inte
pbm2g3: komut yok
pbm2g3: nie znaleziono polecenia
pbm2g3: níor aimsíodh an t-ordú
pbm2g3: no se encontró la orden
pbm2g3: no s'ha trobat l'ordre
pbm2g3: opdracht niet gevonden
pbm2g3: parancs nem található
pbm2g3: perintah tidak ditemukan
pbm2g3: príkaz nenájdený
pbm2g3: příkaz nenalezen
pbm2g3: команда не найдена
pbm2g3: командата не е открита
pbm2g3: 命令找不到
pbm2g3: コマンドが見つかりません