mjhjmtu

I'm looking for a portable way to resolve relative paths into absolute paths while not resolving any symbolic links.

For example, run the following file /home/nat/cat/bat/hat.sh in bash:

set -x
pwd
# cat is a symlink
readlink -e ..
# abs is an imaginary function that returns the path in the form specified by this question 
abs ..
abs /home/./nat/../nat/cat

Output:

+ pwd
/home/nat/cat/bat
+ readlink -e ..
/home/nat/cat-1.12.0
+ abs ..
/home/nat/cat
+ abs /home/./nat/../nat/cat
/home/nat/cat

Unfortunately I cannot use realpath -s for this, as it is not available by default on OSX.

This is how your imaginary function may look materialized:

abs () 
 local _PWD _BN
 [ -d "$1" ] && _PWD="$1"
 [ -f "$1" ] && _PWD=$(dirname "$1") ; _BN=/$(basename "$1") ;
 pushd $_PWD >/dev/null
 echo $(pwd)$_BN
 popd >/dev/null

You can pass either file or directory path as parameter.
it then will go to the specified path and print out working directory then that is what you want.
You may want to add some validations around against empty parameter, non-existing path or insufficient permissions etc. according to your specific needs - I ommitted that from this example.

the pushd/popd pair performs the jump to the target and back

>/dev/null prevents these commands from printing out directory stack what they by default do and that would spoil the desired output