cheap idempotent file fetching

fix-missing.sh

#!/usr/bin/env bash

# given a single case id (e.g., 19820427023459I) will check to see if
# it exists in the output directory, otherwise fetch it --
# it won't store the file if there's a problem with the request

# usage: ./fix-missing.sh <case_id>
if [ `ls out/${1}.html 2> /dev/null` ]; then
  exit
else
  curl -f -s -o out/${1}.html \
    "https://www.asias.faa.gov/apex/f?p=100:18:::NO::AP_BRIEF_RPT_VAR:${1}"
fi

# BEST USED when chained together with a file of IDs and xargs in parallel:
# cat id_list.txt | xargs -I{} -n 1 -P 32 ./fix-missing.sh {}