pbmtextps: 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/pbmtextps - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pbmtextps - from package: netpbm

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

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