What is the difference between "./command" and "bash command"

There is a BIG difference.

Lets take the following script called testscript (configured to use /bin/ksh as you see in the hashbang):

#!/bin/ksh

#im testscript

cd /proc/$$

file exe

First lets execute it with ./:

$ ./testscript

exe: symbolic link to /bin/ksh93

Now calling bash:

$ bash testscript

exe: symbolic link to /bin/bash

The interpreter used by the script changed in the second command, so if the script depends in some ksh specific code it will be broken, and in other way if the scripts depends on bash specific code, then will broke it with the first command.

Other test you can do is to echo $PATH in the two different cases of execution.

3 years ago