Bash Evaluation

Question

I know that in Bash if statements can be evaluated with expr by using:

if [[ 5 > 0 ]]; then echo true; fi

How does Bash evaulate the following form of if?

if [ 5 -gt 0 ]; then echo true; fi

Answer 1

The first one perform a string lexicographic comparison and is bash only, while the second perform a numeric comparison and works also in POSIX shell.

The second one could be better written in bash as

if ((5 > 0)); then echo "true"; fi