configure

#!/bin/bash

# Check that we have at least Bash 3.0 (need it for =~)
if test $BASH_VERSINFO -lt 3; then
    echo "You need Bash 3.0 or newer to run this script."
    exit
fi

# First, print help message if needed
for arg in "$@"; do
    if test "$arg" = "--help"; then
        echo "
This script allows you to modify the behaviour of subsequent 'make' commands.

Any argument of the form --VARIABLE=VALUE will set the Makefile variable
VARIABLE to the value VALUE in the Makefile. Some common variables are

  --prefix=<DIRECTORY>
        Where to install the program. The default is '/usr/local'.
  --CFLAGS=<COMPILER FLAGS>
        Extra compiler flags that will be passed to the compiler in
        the Makefile. The default is '-g -O2'. In you want to turn off
        debugging and optimise more you could use '--CFLAGS=\"-DNDEBUG -O6\".
  --LDFLAGS=<LINKER FLAGS>
        Extra linker flags that will be passed to the linker in
        the Makefile. The default is no extra flags.

All variables can also be overridden by passing a parameter of the form
VARIABLE=VALUE to the 'make' command, e.g. 'make CFLAGS=-DNDEBUG install'.
"
        true
        exit
    fi
done


# Parse parameters
echo __path_to_configure = $0 > Makefile.config.tmp
for arg in "$@"; do
    if [[ $arg =~ --[0-9a-zA-Z_]+=.* ]]; then
        echo $arg | sed 's/--\([0-9a-zA-Z_]\+\)=\(.*\)/\1\ =\ \2/' >> Makefile.config.tmp
    else
        echo "'$arg' is not a valid parameter to configure!"
        exit
    fi
done
rm -f Makefile.config
mv Makefile.config.tmp Makefile.config
echo "
Current configuration:
"
cat Makefile.config | awk '{print "  " $0}'
echo "
Now run 'make install' to install your software!"