#! /bin/bash

if [ "$#" -lt 1 ];then

    echo "Usage: $0 file1 [file2 ...]" >&2

    exit 1

fi

# detect format

format=""

for filename in "$@";do

    if [ "${filename/%.gz}" != "$filename" ];then

        new_format="gzip"

    elif [ "${filename/%.xz}" != "$filename" ];then

        new_format="xz"

    elif [ "${filename/%.bz2}" != "$filename" ];then

        new_format="bzip2"

    else

        new_format="raw"

    fi

    if [ -z "$format" ];then

        format="$new_format"

    fi

    if [ "$new_format" != "$format" ];then

        echo "Error: different format found in input files" >&2

        exit 1

    else

        format="$new_format"

    fi

done

# uncompress files

if [ "$format" = "gzip" ];then

    exec gzip -d -c "$@"

elif [ "$format" = "bzip2" ];then

    exec bzip2 -d -c "$@"

elif [ "$format" = "xz" ];then

    exec xz -d -c "$@"

else

    exec cat "$@"

fi