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@fago
Created March 17, 2014 20:59
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Inotify script to trigger a command on file changes, e.g. rsync
#!/bin/bash
# (c) Wolfgang Ziegler // fago
#
# Inotify script to trigger a command on file changes.
#
# The script triggers the command as soon as a file event occurs. Events
# occurring during command execution are aggregated and trigger a single command
# execution only.
#
# Usage example: Trigger rsync for synchronizing file changes.
# ./watch.sh rsync -Cra --out-format='[%t]--%n' --delete SOURCE TARGET
######### Configuration #########
EVENTS="CREATE,CLOSE_WRITE,DELETE,MODIFY,MOVED_FROM,MOVED_TO"
COMMAND="$@"
WATCHDIR=$PROJECT_DIR/web
## Exclude Git and temporary files from PHPstorm from watching.
EXCLUDE='(\.git|___jb_|sites/default/dev)'
## Whether to enable verbosity. If enabled, change events are output.
VERBOSE=0
##################################
if [ -z "$1" ]; then
echo "Usage: $0 Command"
exit 1;
fi
##
## Setup pipes. For usage with read we need to assign them to file descriptors.
##
RUN=$(mktemp -u)
mkfifo "$RUN"
exec 3<>$RUN
RESULT=$(mktemp -u)
mkfifo "$RESULT"
exec 4<>$RESULT
clean_up () {
## Cleanup pipes.
rm $RUN
rm $RESULT
}
## Execute "clean_up" on exit.
trap "clean_up" EXIT
##
## Run inotifywait in a loop that is not blocked on command execution and ignore
## irrelevant events.
##
inotifywait -m -q -r -e $EVENTS --exclude $EXCLUDE --format '%w%f' $WATCHDIR | \
while read FILE
do
if [ $VERBOSE -ne 0 ]; then
echo [CHANGE] $FILE
fi
## Clear $PID if the last command has finished.
if [ ! -z "$PID" ] && ( ! ps -p $PID > /dev/null ); then
PID=""
fi
## If no command is being executed, execute one.
## Else, wait for the command to finish and then execute again.
if [ -z "$PID" ]; then
## Execute the following as background process.
## It runs the command once and repeats if we tell him so.
($COMMAND; while read -t0.001 -u3 LINE; do
echo running >&4
$COMMAND
done)&
PID=$!
WAITING=0
else
## If a previous waiting command has been executed, reset the variable.
if [ $WAITING -eq 1 ] && read -t0.001 -u4; then
WAITING=0
fi
## Tell the subprocess to execute the command again if it is not waiting
## for repeated execution already.
if [ $WAITING -eq 0 ]; then
echo "run" >&3
WAITING=1
fi
## If we are already waiting, there is nothing todo.
fi
done
@juxliano
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Thanks for this! Worked pretty well to me!

@bartzwemmer
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Works great and easy to modify. Only thing is that I get an error: line 75: read: Illegal option -t. I think it should be -t 0.001 (with an extra space)?

@mmallejac
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Great ! Thanks for sharing this, very useful.
I use it to let Nextcloud know about changes made on some files.

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