From aea6bd4816fa9303c1e2bcc568f7ee0d6505442f Mon Sep 17 00:00:00 2001
From: Kenneth Hoste <kenneth.hoste@ugent.be>
Date: Thu, 6 Jan 2022 18:09:47 +0100
Subject: [PATCH] avoid excessively long shebang line in compile script for WRF

---
 easybuild/easyblocks/w/wrf.py | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/easybuild/easyblocks/w/wrf.py b/easybuild/easyblocks/w/wrf.py
index 3751a66c049..7f62d68b184 100644
--- a/easybuild/easyblocks/w/wrf.py
+++ b/easybuild/easyblocks/w/wrf.py
@@ -44,7 +44,8 @@
 from easybuild.framework.easyconfig import CUSTOM, MANDATORY
 from easybuild.tools.build_log import EasyBuildError
 from easybuild.tools.config import build_option
-from easybuild.tools.filetools import apply_regex_substitutions, change_dir, patch_perl_script_autoflush, read_file
+from easybuild.tools.filetools import apply_regex_substitutions, change_dir
+from easybuild.tools.filetools import patch_perl_script_autoflush, read_file, which
 from easybuild.tools.filetools import remove_file, symlink
 from easybuild.tools.modules import get_software_root
 from easybuild.tools.run import run_cmd, run_cmd_qa
@@ -252,11 +253,26 @@ def build_step(self):
         if par:
             self.par = "-j %s" % par
 
-        # fix compile script shebang
+        # fix compile script shebang to use provided tcsh
         cmpscript = os.path.join(self.start_dir, 'compile')
-        cmpsh_root = get_software_root('tcsh')
-        if cmpsh_root:
-            regex_subs = [('/bin/csh', os.path.join(cmpsh_root, 'bin/tcsh'))]
+        tcsh_root = get_software_root('tcsh')
+        if tcsh_root:
+            tcsh_path = os.path.join(tcsh_root, 'bin', 'tcsh')
+            # avoid using full path to tcsh if possible, since it may be too long to be used as shebang line
+            which_tcsh = which('tcsh')
+            if which_tcsh and os.path.samefile(which_tcsh, tcsh_path):
+                env_path = os.path.join('/usr', 'bin', 'env')
+                # use env command from alternate sysroot, if available
+                sysroot = build_option('sysroot')
+                if sysroot:
+                    sysroot_env_path = os.path.join(sysroot, 'usr', 'bin', 'env')
+                    if os.path.exists(sysroot_env_path):
+                        env_path = sysroot_env_path
+                new_shebang = env_path + ' tcsh'
+            else:
+                new_shebang = tcsh_path
+
+            regex_subs = [('^#!/bin/csh.*', '#!' + new_shebang)]
             apply_regex_substitutions(cmpscript, regex_subs)
 
         # build wrf