Adding to /etc/profile.d from bash script fails - bash

Question

I have the following problem. I need to create system-wide JDK_HOME and JAVA_HOME variables. First I want to create /etc/profile.d/java.sh and add
JDK_HOME to it. Then I want to append JAVA_HOME to this file. So far I have this code.
#!/bin/bash
create_env_var()
{
local varname="$1"
local varvalue="$2"
local filename="/etc/profile.d/$3"
if [ -e "$filename" ]; then
echo "**ERROR: file $filename already exists"
else
sh -c 'echo "$varname=$varvalue" > $filename'
chmod +x "$filename"
fi
}
append_env_var()
{
local varname="$1"
local varvalue="$2"
local filename="/etc/profile.d/$3"
if [ ! -e "$filename" ]; then
echo "**ERROR: file $filename not found"
else
sh -c 'echo "$varname=$varvalue" >> $filename'
chmod +x "$filename"
fi
}
create_env_var "JDK_HOME" "/usr/lib/jvm/java-7-openjdk-i386" "java.sh"
append_env_var "JAVA_HOME" "/usr/lib/jvm/java-7-openjdk-i386" "java.sh"
exit "$?"
However these lines don't work and I see the following errors:
sh: 1: cannot create : Directory nonexistent
chmod: cannot access ‘/etc/profile.d/java.sh’: No such file or directory
Would you please show me where everything goes wrong?

Answer 1

While you can remove the single quotes, there's no reason to create a subprocess and use sh -c.
change sh -c 'echo "$varname=$varvalue" > $filename'
to echo "$varname=$varvalue" > $filename
and sh -c 'echo "$varname=$varvalue" >> $filename'
to echo "$varname=$varvalue" >> $filename