Is there some shell full path function? [duplicate]

Question

This question already has answers here:

How to obtain the absolute path of a file via Shell (BASH/ZSH/SH)? (22 answers)

Closed 8 years ago.

Is there some native function(shell, linux command) to merge/compute the full path?

example:

old_path="~/test1/test2/../dir3//file.txt"
new_path=FUN($old_path)

echo "$new_path"   // I want get this "/home/user/test1/dir3/file.txt"    

Answer 1

Use readlink:

$ readlink -m ~/foo.txt
/home/user/foo.txt
$ readlink -m ~/somedir/..foo.txt
/home/user/foo.txt

It also handles symlinks.

Answer 2

Does

  new_path=$(eval cd "$old_path"; pwd)

work for you? You can also use pwd -P if you want symlinks resolved. You can make life easier if you use $HOME instead of ~ in old_path. Then you don't need the eval.