check_filedeps.sh

#!/bin/bash

# usage: [required_input ...]
#        --optional [optional_inputs ...]
#        --required [required_inputs ...]
#        --output=[output]
#        [--skip-mtime]
# This script will fail if all inputs are older than the output file or if
# the output file does not exits.
# If --skip-mtime is provided, only the existance of files will be checked.

# Parse command line args
inputs=()
optional_inputs=()
optional=false
skip_mtime=false
for i in "$@"
do
    case $i in
        --output=*)
            output="${i#*=}"
            shift
            ;;
        --skip-mtime)
            skip_mtime=true
            shift
            ;;
        --optional)
            optional=true
            shift
            ;;
        --required)
            optional=false
            shift
            ;;
        *)
            if [[ $optional = true ]]; then
                optional_inputs+=($i)
            else
                inputs+=($i)
            fi
            shift
            ;;
    esac
done

for input in ${inputs[@]}; do
    if [[ ! -f $input ]]; then
        exit 1
    fi
done
if [[ ! -f $output ]]; then
    exit 0
fi
if [[ $skip_mtime = true ]]; then
    exit 0
fi
all_inputs=(${inputs[@]} ${optional_inputs[@]})
for input in ${all_inputs[@]}; do
    if [[ -f $input ]] && [[ $output -ot $input ]]; then
        exit 0
    fi
done
exit 1