Why is bash language often slower than python or ruby?

I assume it is because of the interpreter's implementation. Can开发者_运维技巧 anyone give me a more in-depth answer please? Thanks.

Also, I wonder if bash has a garbage collector?

bash loads a large number of commands from disk. Most other scripting languages have many more instructions that they run internally.

For example, to do a simple computation in bash, you'd use a=`expr 1 + 2` and bash will first load /usr/bin/expr, run that command which writes the result in the output, bash collects the output (the ` quotes) and saves the result in the variable 'a'. That's definitively slow.

The advantage of bash is the incredible flexibility though. Each person may have a different set of powerful "instructions". For example, I have a small tool called hex to print out numbers in octal, hexadecimal and decimal all at once. Other languages would not integrate in the way bash does...