Bash File Mirror Script via HTTP

file-mirror-scipt

#!/bin/bash

# A bash script for mirroring a file
# Exit codes:
# -1 = local file up to date, nothing to do
# 0 = updated local file, successfull
# 1 (and above) = failure

# Written by Jack Henschel for https://cubieserver.de/blog/ 

REMOTE_FILE="https://kernel.org/index.html";
LOCAL_FILE="mirror.html";
V=1 # Verbosity: 0 for quiet, 1 for normal

# Check if the remote file is available
if [[ $( curl -s -o /dev/null -w "%{http_code}" "$REMOTE_FILE" ) != 200 ]]; then
	if [ $V -gt 0 ]; then
		echo "Error while checking for remote file $REMOTE_FILE";
	fi
	exit 1;
fi

# Check the local file (existence and permissions)
if [[ -e "$LOCAL_FILE" ]] && [[ ! -w "$LOCAL_FILE" ]]; then
	if [ $V -gt 0 ]; then
		echo "Error: no write permisssions on local file $LOCAL_FILE";
	fi
	exit 1;
fi

# Get date of remote file
REMOTE_DATE=$( date -d "$( curl -Is $REMOTE_FILE | grep 'Modified' | cut -d',' -f2 )" "+%s" );
# Check if we actually got only a digit
if [[ ! "$REMOTE_DATE" =~ [[:digit:]] ]]; then
	if [ $V -gt 0 ]; then
		echo "Error while parsing remote date: $REMOTE_DATE";
	fi
	exit 1;
fi

# Get date of local file
if [[ -e "$LOCAL_FILE" ]]; then
	LOCAL_DATE=$( stat "$LOCAL_FILE" -c "%Y" );
else
	LOCAL_DATE=0;
	touch "$LOCAL_FILE" >> /dev/null 2>&1;
	if [ $? -eq 1 ]; then
		if [ $V -gt 0 ]; then
			echo "Error: could not create local file $LOCAL_FILE";
		fi
		exit 1;
	fi
fi

# Check if we actually got only a digit
if [[ ! "$LOCAL_DATE" =~ [[:digit:]] ]]; then
	if [ $V -gt 0 ]; then
		echo "Error while parsing local date: $LOCAL_DATE";
	fi
	exit 1;
fi

# Check if local file is younger than remote file
if [ $LOCAL_DATE -gt $REMOTE_DATE ]; then
	if [ $V -gt 0 ]; then
		echo "File is up to date";
	fi
	exit -1;
else
	curl -s "$REMOTE_FILE" -o "$LOCAL_FILE";
	if [ $V -gt 0 ]; then
		echo "File has been updated";
	fi
fi

exit 0;