Question: As stated in the title, I need to determine when a program is ran if the path is relative or absolute:

```
./program #relative
dir/dir2/program #relative
~User/dir/dir2/program #absolute
/home/User/dir/dir2/program #absolute

```

This are my test cases. How exactly could I go about doing this in a shell program? 

Or more generally, how to check if a path, `$0` in this case, is relative or absolute?

Answer: 
A general solution for any `$path`, rather than just `$0`

### POSIX One Liner

```sh
[ "$path" != "${path#/}" ] && echo "absolute" || echo "relative"

```
```
if [ ${path:0:1} == / ]
then
     echo Absolute path
else
     echo Non-absolute path
fi

```