Watch current directory and execute a command if anything in it changes

onchange.sh

#!/bin/bash
#
# Watch current directory (recursively) for file changes, and execute
# a command when a file or directory is created, modified or deleted.
#
# Written by: Senko Rasic <senko.rasic@dobarkod.hr>
#
# Requires Linux, bash and inotifywait (from inotify-tools package).
#
# To avoid executing the command multiple times when a sequence of
# events happen, the script waits one second after the change - if
# more changes happen, the timeout is extended by a second again.
#
# Installation:
#     chmod a+rx onchange.sh
#     sudo cp onchange.sh /usr/local/bin
#
# Example use - rsync local changes to the remote server:
#    
#    onchange.sh rsync -avt . host:/remote/dir
#
# Released to Public Domain. Use it as you like.
#

EVENTS="CREATE,CLOSE_WRITE,DELETE,MODIFY,MOVED_FROM,MOVED_TO"

if [ -z "$1" ]; then
    echo "Usage: $0 cmd ..."
    exit -1;
fi

inotifywait -e "$EVENTS" -m -r --format '%:e %f' . | (
    WAITING="";
    while true; do
        LINE="";
        read -t 1 LINE;
        if test -z "$LINE"; then
            if test ! -z "$WAITING"; then
                    echo "CHANGE";
                    WAITING="";
            fi;
        else
            WAITING=1;
        fi;
    done) | (
    while true; do
        read TMP;
        echo $@
        $@
    done
)

If you change "$@" to "eval $@" you will be able to run several commands.
Example:
onchange.sh "rsync dest orig && notify-send Sucess || notify-send Failure"

15 minutes

!/bin/bash

if [ "$1"x = ""x ]; then
cat<<EOF
Watches for changes recursively, then goes on to execute your command
or script. It wait 2.5 minutes between executes. Good for syncing
directories or doing dynamic backups.
by Hydranix

Usage: DetectChanges "[ directory to watch ]" "[ command/script to execute ]" "[optional: time in second between executes]"
EOF
exit 0;
fi
while [ ! -f /tmp/EXITHNx ]; do
sleep 3
inotifywait -r -e create -e delete -e move "${1}" &>/dev/null
XSTA=$?
if [ "$XSTA" = "0" ]; then
eval ${2}
else
touch /tmp/EXITHNx
exit 1
fi
[[ -z ${3} ]] && sleep 150 || sleep ${3}
done
rm -f /tmp/EXITHNx

Unfortunately inotifywait does not work with mounted folders. I wanted to use it in my vagrant box, to copy files from eg. /vagrant/www/ to /var/www/ (which is the document root of apache). Mounting files directly to document root slows down php very much, so I thought this would be a nice idea.

@ArminVieweg Did you eventually find a solution for that? It's precisely what I was looking to do.

The version with eval published by @evgenius https://gist.github.com/evgenius/6019316

What will be the benefit of running onchange.sh every x minutes (to trigger rsync) versus running rsync every x minutes? Is it just less demanding on the server?

why not use watch in homebrew?

brew info watch

source code here:https://gitlab.com/procps-ng/procps

Because not everyone runs Mac?

Why can't I kill it with ctrl + c?

Nice script! Thanks 👍
I'm using rsync to synchronize my local dir to a remote server's dir, which is working great, but I have to enter my password on every sync. Any ideas on how I could sync fully automatically (without having to enter the password)?
Unfortunately I can't setup an ssh key and use it to authenticate, since the remote is shared and crappy..

Cool idea, but how would you pass extra arguments with quotes? say i want onchange.sh rsync -a --exclude='folder with space' host:/path?

Thanks for the script! I'm having trouble figuring out where the 1 second is defined, as I'd like to extend it.

@tdmalone, read -t 1 LINE tries to read one line, but with a one second timeout. read is a bash builtin, and is documented on the bash man page.