favicon-fetch

#!/bin/sh
set -euf

## Program Tracking ##

program_command="favicon-fetch"
program_version="1.5.0"
program_created="2015-05-31"
program_updated="2016-02-11"
program_license="GPL"
program_contact="Joel Parker Henderson (joel@joelparkerhenderson.com)"
program_variant="$program_command version $program_version updated $program_updated"

## Help Function ##

help(){
cat <<EOF
favicon-fetch:
connect to a web site or web page then download its favicon.ico file.

Syntax:

    favicon-fetch <url>

Example:

    favicon-fetch https://www.example.com
    => download favicon.ico file

Command: $program_command
Version: $program_version
Created: $program_created
Updated: $program_updated
License: $program_license
Contact: $program_contact
EOF
}

## Essential Functions ##

out () { printf %s\\n "$*" ; }
err () { >&2 printf %s\\n "$*" ; }
die () { >&2 printf %s\\n "$*" ; exit 1 ; }
die_opt_unk() { die "Option $1 is unknown" ; }
die_opt_arg() { die "Option $1 needs an argument" ; }


if [ $# -eq 0 ]
then
  out "Syntax: fetch-favicon <url>"
  out "Example: fetch-favicon www.example.com"
  exit
fi

page_url=$1
out "page_url:$page_url"

icon_url=$(curl -s -S -L "$page_url" | pup 'link[rel~="icon"] attr{href}' | head -1)
out "icon_url:$icon_url"

icon_file_name=$(out "$icon_url" | uri-scheme file)
out "icon_file_name:$icon_file_name"

icon_abs_url=$(uri-relate "$page_url" "$icon_url")
out "icon_abs_url:$icon_abs_url"

curl -s -S -L "$icon_abs_url" -o "$icon_file_name"