log2graph: 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/log2graph - from package: octomap

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

On Debian possible default full paths are:

/usr/bin/log2graph - from package: octomap-tools

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

Error in other languages:
log2graph: bevel nie gevind nie
log2graph: comandă negăsită
log2graph: comando não encontrado
log2graph: commande introuvable
log2graph: command not found
log2graph: käsku ei ole
log2graph: không tìm thấy lệnh
log2graph: komanda nerasta
log2graph: Kommando nicht gefunden.
log2graph: kommandot finns inte
log2graph: komut yok
log2graph: nie znaleziono polecenia
log2graph: níor aimsíodh an t-ordú
log2graph: no se encontró la orden
log2graph: no s'ha trobat l'ordre
log2graph: opdracht niet gevonden
log2graph: parancs nem található
log2graph: perintah tidak ditemukan
log2graph: príkaz nenájdený
log2graph: příkaz nenalezen
log2graph: команда не найдена
log2graph: командата не е открита
log2graph: 命令找不到
log2graph: コマンドが見つかりません