scripts: apply realpath for $0

[jengelh]

When $0 is a symlink, program execution would fail to find the right
directory. Fix that up.

The 4ti2 program names are quite generic (e.g. "output"), and hence
openSUSE has relegated them to /usr/libexec/4ti2, offering instead
prefixed symlinks in /usr/bin, e.g. /usr/bin/4ti2_groebner ->
/usr/libexec/4ti2/groebner.

[mkoeppe]

The 4ti2 program names are quite generic (e.g. "output"), and hence
openSUSE has relegated them to /usr/libexec/4ti2, offering instead
prefixed symlinks in /usr/bin, e.g. /usr/bin/4ti2_groebner ->
/usr/libexec/4ti2/groebner.

Note that Debian uses 4ti2-groebner (dash, not underscore) -- perhaps you can follow their naming?

[jengelh]

This PR is independent of the particular symlink names used on a given system; the use of realpath is valid for all scenarios, including non-symlinked cases.

Since the symlinking in distros is a hack of sorts, the only comfortable change would be if the naming is changed by the 4ti2 project itself, and globally for all its users (cf. issue #22).

[mkoeppe]

Does ./configure --program-prefix=4ti2_ not work?

[jengelh]

1. 4ti2gmp would be installed as /usr/bin/4ti2_4ti2gmp (double prefix of sorts)
2. zsolve would be installed as /usr/bin/4ti2_zsolve, but the /usr/bin/4ti2_graver script would still try to execute zsolve.
   So no, --program-prefix is not yet a working route.

[mkoeppe]

I tend to issues on a schedule that I set

[jengelh]

Github autoclosed the ticket when the source repo is removed (even though the ref might survive in the target repo so that merging remains possible) and attributes it to the original opener.