Question

I need to execute shell command in python program (I have ubuntu). More specifically I want to create graph using graphviz in python script. My code is

os.system("dot -Tpng graph.dot -o graph.png")

It does not work, but if I just type “dot -Tpng graph.dot -o graph.png” in command line then everything is fine. Do you know what the problem? Thank you!

Edit: does not work means that nothing happens, there are no errors.

Output from “dot -v -Tpng graph.dot -o graph.png”

dot - graphviz version 2.26.3 (20100126.1600)

Activated plugin library: libgvplugin_pango.so.6
Using textlayout: textlayout:cairo
Activated plugin library: libgvplugin_dot_layout.so.6
Using layout: dot:dot_layout
Using render: cairo:cairo
Using device: png:cairo:cairo
The plugin configuration file:
/usr/lib/graphviz/config6
was successfully loaded.
render : cairo dot fig gd map ps svg tk vml vrml xdot
layout : circo dot fdp neato nop nop1 nop2 osage patchwork sfdp twopi
textlayout : textlayout
device : canon cmap cmapx cmapx_np dot eps fig gd gd2 gif gv imap imap_np ismap jpe jpeg jpg pdf plain plain-ext png ps ps2 svg svgz tk vml vmlz vrml wbmp x11 xdot xlib
loadimage : (lib) eps gd gd2 gif jpe jpeg jpg png ps svg

Answer 1

I figured out the problem. I should close file graph.dot before executing the command.