Combine multiple .a static libraries, which may each have multiple architectures, into a single static library

combine_static_libraries.sh

#!/bin/sh

# Combined all static libaries in the current directory into a single static library
# It is hardcoded to use the i386, x86_64, armv7, armv7s and arm64 architectures; this can easily be changed via the 'archs' variable at the top
# The script takes a single argument, which is the name of the final, combined library to be created.
#
#   For example:
#  =>    combine_static_libraries.sh combined-library
#
# Script by Evan Schoenberg, Regular Rate and Rhythm Software
# Thanks to Claudiu Ursache for his blog post at http://www.cvursache.com/2013/10/06/Combining-Multi-Arch-Binaries/ which detailed the technique automated by this script
#####
# $1 = Name of output archive
#####

archs=(i386 x86_64 armv7 armv7s arm64)
libraries=(*.a)
libtool="/usr/bin/libtool"

echo "Combining ${libraries[*]}..."

for library in ${libraries[*]}
do
    lipo -info $library

    # Extract individual architectures for this library
    for arch in ${archs[*]}
    do
            lipo -thin $arch $library -o ${library}_${arch}.a
    done
done

# Combine results of the same architecture into a library for that architecture
source_combined=""
for arch in ${archs[*]}
do
    source_libraries=""
   
    mkdir $arch
    cd $arch
    for library in ${libraries[*]}
    do
        # Extract the libraries, overwriting duplicated files with the same name in each lib
        ar x ../${library}_${arch}.a
        rm __.SYMDEF
        # Hack specific to one usecase: don't deduplicate Utils.o, both versions must be kept
        mv Utils.o ${library}_Utils.o
        source_libraries="${source_libraries} ${library}_${arch}.a"
    done
    cd ..
    
    $libtool -static ${arch}/*.o -o "${1}_${arch}.a"
    source_combined="${source_combined} ${1}_${arch}.a"
    
    # Delete intermediate files
    rm ${source_libraries}
    rm -rf ${arch}
done

# Merge the combined library for each architecture into a single fat binary
lipo -create $source_combined -o $1.a

# Delete intermediate files
rm ${source_combined}

# Show info on the output library as confirmation
echo "Combination complete."
lipo -info $1.a