what's wrong with my shell

[mzzz]

hey, guys~
I'm kinda new to shell programming on linux. my code is as follows:

#!/bin/bash
a = 111
echo $a
read -p "..."

and the execution result is:
a: command not found

It's a simple assignment to variable a. i made reference to some websites, it seams there is no mistake, so what's wrong?

[Peter87]

Remove the spaces around =.

a=111

[mzzz]

Thanks your very much@Peter87.
Another more question. are there some tools can help you to debug shell code? like seting breakpoints, watching values etc?

[tcs]

Include f.e.

# Code not being debugged
set -vx
# Your code to be debugged
set +vx
# Code not being debugged 

The debug output wil be written to stderr. So you may want to redirect stderr to a text file to not confuse your programs IO.