import os

shell.executable("bash")


def get_mem_gb(wildcards, input):
    size = 0
    if os.path.exists(input[0]):
        size = int(os.path.getsize(input[0]) / (1024 ** 3))
    return max(size, 1)


rule a:
    input:
        "test1.in",
        "test2.in"
    output:
        "test.out"
    params:
        a=lambda wildcards, input, resources: "+".join(input)
    resources:
        mem_gb=get_mem_gb
    shell:
        "echo {params.a} > {output}"
