Problem with bash script

If running pid=`/bin/cat pid/order_$name` and leave...

1) it may need the absolute path to the pid file
2) and use /bin/cat. What's the problem then?

Purely theoretical interest. Such problems may arise with other operators that will be uncomfortable.
\r
In the beginning of the script spelled out the absolute path. The problem is not with paths.
\r
And on another server with very similar configuration everything works with '<'.

I use brackets instead of quotes, can you help?
pid=$(/bin/cat ./pid/order_$name)