potrace: 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/potrace - from package: potrace

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

On Debian possible default full paths are:

/usr/bin/potrace - from package: potrace

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

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