realpath does not exist on Mac

[vfrinken]

trying to install Idris2 in a Mac using
make bootstrap SCHEME=chez
aborts with an error message that realpath cannot be found, which is not surprising, since realpath doesn't exist.

i propose to include something like this

realpath() {
  OURPWD=$PWD
  cd "$(dirname "$1")"
  LINK=$(readlink "$(basename "$1")")
  while [ "$LINK" ]; do
    cd "$(dirname "$LINK")"
    LINK=$(readlink "$(basename "$1")")
  done
  REALPATH="$PWD/$(basename "$1")"
  cd "$OURPWD"
  echo "$REALPATH"
}

(found in whatwg/html-build#90)

[keram]

Hi @vfrinken realpath is required for installation and as mentioned in https://github.com/idris-lang/Idris2/blob/master/INSTALL.md you can install it on Mac as part of coreutils
brew install coreutils
cheers!

[ska80]

I believe this issue can be closed.

[gallais]

Can we check in the makefile that the required dependencies are
installed & complain if it's not the case?

[ska80]

Can we check in the makefile that the required dependencies are
installed & complain if it's not the case?

This PR #1210 checks if realpath exists for Chez and Racket backends. I didn't put this check in the makefile because only Chez and Racket use realpath at the moment.

[benhormann]

Can we check in the makefile that the required dependencies are
installed & complain if it's not the case?

Not really, it is also a runtime dependency i.e. compiled "Hello world" app includes same script.

Racket's raco exe has an option to include libs, maybe it is possible to embed the support lib? Chez mentions concatenating object files. Failing that, a shell imitation of realpath isn't a bad way to go (easy to fix when it breaks).

---

## The following is equivalent to: DIR=$(dirname $(realpath $0))
## Non-GNU systems don't always have realpath/grealpath installed.
DIR=$PWD
LINK=$0
while [ -n "$LINK" ]; do
  # If LINK is not absolute, join with DIR.
  [ -n "${LINK##/*}" ] && LINK=$DIR/$LINK
  DIR=$(dirname "$LINK")
  LINK=$(readlink "$LINK")
done
# Canonicalize path.
DIR=$(cd -P "$DIR" && pwd -P)
# Note: For non-POSIX systems, try without the -P option.
ERR=$?; [ 0 = $ERR ] || {
  echo "Script '$0' expects POSIX shell and read access." >&2
  exit $ERR
}

Should work on all modern systems, so let's replace the whole case `uname` block?
This way , "\"`dirname \"$DIR\"`\"/\"" ++ target ++ "\" \"$@\"" becomes , "\"$DIR/" ++ target ++ "\" \"$@\"".

Caveat: cd -P only works on POSIX systems, according to: https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.70/html_node/Limitations-of-Builtins.html#index-cd
For such old shells, the $() and ${} syntax might not work either.