diff -up src/sage/env.py.orig src/sage/env.py
--- src/sage/env.py.orig	2021-05-29 21:01:26.503474025 -0600
+++ src/sage/env.py	2021-05-29 21:03:06.389635554 -0600
@@ -166,16 +166,16 @@ SAGE_DATE = var("SAGE_DATE", version.dat
 SAGE_VERSION_BANNER = var("SAGE_VERSION_BANNER", version.banner)
 
 # virtual environment where sagelib is installed
-SAGE_VENV = var("SAGE_VENV", os.path.abspath(sys.prefix))
+SAGE_VENV = var("SAGE_VENV", "@@SAGE_LOCAL@@")
 SAGE_LIB = var("SAGE_LIB", os.path.dirname(os.path.dirname(sage.__file__)))
-SAGE_EXTCODE = var("SAGE_EXTCODE", join(SAGE_LIB, "sage", "ext_data"))
+SAGE_EXTCODE = var("SAGE_EXTCODE", join("/usr", "share", "sagemath", "etc"))
 
 # prefix hierarchy where non-Python packages are installed
 SAGE_LOCAL = var("SAGE_LOCAL", SAGE_VENV)
-SAGE_ETC = var("SAGE_ETC", join(SAGE_LOCAL, "etc"))
-SAGE_INC = var("SAGE_INC", join(SAGE_LOCAL, "include"))
-SAGE_SHARE = var("SAGE_SHARE", join(SAGE_LOCAL, "share"))
-SAGE_DOC = var("SAGE_DOC", join(SAGE_SHARE, "doc", "sage"))
+SAGE_ETC = var("SAGE_ETC", join("/usr", "share", "sagemath", "etc"))
+SAGE_INC = var("SAGE_INC", join("/usr", "include"))
+SAGE_SHARE = var("SAGE_SHARE", join("/usr", "share", "sagemath"))
+SAGE_DOC = var("SAGE_DOC", join("/usr", "share", "doc", "sagemath"))
 SAGE_SPKG_INST = var("SAGE_SPKG_INST", join(SAGE_LOCAL, "var", "lib", "sage", "installed"))
 
 # source tree of the Sage distribution
@@ -199,12 +199,12 @@ THEBE_DIR = var("THEBE_DIR", join(SAGE_S
 COMBINATORIAL_DESIGN_DATA_DIR = var("COMBINATORIAL_DESIGN_DATA_DIR", join(SAGE_SHARE, "combinatorial_designs"))
 CREMONA_MINI_DATA_DIR = var("CREMONA_MINI_DATA_DIR", join(SAGE_SHARE, "cremona"))
 CREMONA_LARGE_DATA_DIR = var("CREMONA_LARGE_DATA_DIR", join(SAGE_SHARE, "cremona"))
-JMOL_DIR = var("JMOL_DIR", join(SAGE_SHARE, "jmol"))
-MATHJAX_DIR = var("MATHJAX_DIR", join(SAGE_SHARE, "mathjax"))
-MTXLIB = var("MTXLIB", join(SAGE_SHARE, "meataxe"))
+JMOL_DIR = var("JMOL_DIR", join("/usr", "share", "java", "jmol"))
+MATHJAX_DIR = var("MATHJAX_DIR", join("/usr", "share", "javascript", "mathjax"))
+MTXLIB = var("MTXLIB", join(DOT_SAGE, "meataxe"))
 THREEJS_DIR = var("THREEJS_DIR", join(SAGE_SHARE, "threejs"))
 SINGULARPATH = var("SINGULARPATH", join(SAGE_SHARE, "singular"))
-PPLPY_DOCS = var("PPLPY_DOCS", join(SAGE_SHARE, "doc", "pplpy"))
+PPLPY_DOCS = var("PPLPY_DOCS", join("/usr", "share", "doc", "python3-pplpy"))
 MAXIMA = var("MAXIMA", "maxima")
 MAXIMA_FAS = var("MAXIMA_FAS")
 SAGE_NAUTY_BINS_PREFIX = var("SAGE_NAUTY_BINS_PREFIX", "")
@@ -301,10 +301,10 @@ def _get_shared_lib_path(*libnames: str)
 
 # locate singular shared object
 # On Debian it's libsingular-Singular so try that as well
-SINGULAR_SO = var("SINGULAR_SO", _get_shared_lib_path("Singular", "singular-Singular"))
+SINGULAR_SO = var("SINGULAR_SO", "@@LIBDIR@@/libSingular.so")
 
 # locate libgap shared object
-GAP_SO = var("GAP_SO", _get_shared_lib_path("gap", ""))
+GAP_SO = var("GAP_SO", "@@LIBDIR@@/libgap.so")
 
 # post process
 if ' ' in DOT_SAGE: