Add a script for linking for debian

What
===
Add a script for linking for debian.

Why
===
The location of java home is different on mac and debian, and on debian
there is no java_home variable to select version 11 of java. The default
jdk installation on debian is currently version 11 and the script uses
that. In the event it is not installed mvn will error because the
JAVA_HOME is pointing to an invalid path. In the event multiple version
of java are installed version 11 will be used regardless of which is set
as the default.

The patch script has been updated to use the JAVA_HOME path explicitly
for each command to ensure it uses the correct version of java when
multiple versions are installed. This is consistent with the link
scripts.

2 files changed, 32 insertions, 5 deletions

diff --git a/scripts/link_debian.sh b/scripts/link_debian.sh
new file mode 100755
index 0000000..183cb99
--- /dev/null
+++ b/scripts/link_debian.sh
@@ -0,0 +1,24 @@
+#!/bin/bash
+# Links everything into a self-contained executable using jlink.
+
+set -e
+
+# Needed if you have a java version other than 11 as default
+JAVA_HOME='/usr/lib/jvm/java-11-openjdk-amd64'
+
+# Compile sources
+mvn compile
+
+# Patch gson
+if [ ! -e modules/gson.jar ]; then
+  ./scripts/patch_gson.sh
+fi
+
+# Build using jlink
+rm -rf dist/debian
+$JAVA_HOME/bin/jlink \
+  --module-path modules/gson.jar:target/classes \
+  --add-modules gson,javacs \
+  --launcher launcher=javacs/org.javacs.Main \
+  --output dist/debian \
+  --compress 2
diff --git a/scripts/patch_gson.sh b/scripts/patch_gson.sh
index d2981ea..348f01f 100755
--- a/scripts/patch_gson.sh
+++ b/scripts/patch_gson.sh
@@ -6,7 +6,10 @@
 set -e
 
 # Needed if you have a java version other than 11 as default
-JAVA_HOME=$(/usr/libexec/java_home -v 11)
+# and used if java_home is available
+if [ -f /usr/libexec/java_home ] ; then
+  JAVA_HOME=$(/usr/libexec/java_home -v 11)
+fi
 
 # Download Gson jar
 cd modules
@@ -15,15 +18,15 @@ curl https://repo1.maven.org/maven2/com/google/code/gson/gson/2.8.5/gson-2.8.5.j
 # Unpack jar into modules/classes
 mkdir classes
 cd classes
-jar xf ../gson.jar
+$JAVA_HOME/bin/jar xf ../gson.jar
 cd ..
 
 # Compile module-info.java to module-info.class
-javac -p com.google.gson -d classes module-info.java
+$JAVA_HOME/bin/javac -p com.google.gson -d classes module-info.java
 
 # Update gson.jar with module-info.class
-jar uf gson.jar -C classes module-info.class
+$JAVA_HOME/bin/jar uf gson.jar -C classes module-info.class
 
 # Clean up
 rm -rf classes
-cd ..
\ No newline at end of file
+cd ..