One common exec issue

I'm often asked to help with exec directive not starting child ffmpeg (or any other process). One common error is the following

• ffmpeg is NOT in /bin or /usr/bin
• full path is not specified in exec, only binary name

In this case exec will not start child process because nginx wipes its environment before starting workers. So child processes have empty PATH variable and cannot find the executable. In such cases the binary is usually looked up in default locations like /bin or /usr/bin.

To solve the issue please add env PATH directive to nginx.conf. It will preserve PATH environment variable.

...
# keep $PATH
env PATH;
...

rtmp {
  server {
    listen 1935;
    application myapp {
        live on;
        exec ffmpeg -i rtmp://localhost/myapp/$name
                    -c copy -f flv rtmp://localhost/app2/$name;
    }
    application app2 {
      live on;
    } 
  }
}