Usage

#Usage

Start ./onfilechange.sh -h to get the help

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  T R I G G E R    C O M M A N D    O N    A    F I L E C H A N G E   
_______________________________________________________________________| v1.06


HELP:

onfilechange.sh checks the change of a given fileobjects and triggers
a command on file changes.
It can use stat or inotifywait to watch a file change. Default is stat because
it can be used for non existing files.

SYNTAX:

  onfilechange.sh OPTIONS [FILE] [[... FILE N]]

PRAMETERS:

  -c|--command COMMAND
    A command to execute on a file change

  -f|--file FILENAME
    Filenames or directories to watch; separate multiple files with 
    space and put all in quotes
    DEPRECATED: add all files to watch as parameters

  -h|--help
    show this help

  -i|--inotifywait
    force inotifywait command

  -s|--stat
    force stat command (default mode)
 
  -v|--verbose
    verbose mode; enable showing debug output; it should be the first option
    to see handling of other options
  
  -w|--wait SLEEPTIME
    for stat mode: wait time in seconds betweeen each test or on 
    missing file; default: 5 sec

EXAMPLES:

  onfilechange.sh -c "ls -l" /home/me/touchfile.txt
    watch touchfile.txt and make a file listing on change
  
  onfilechange.sh -c "ls -l" "/home/me/touchfile.txt" "home/me/touchfile2.txt"
    watch touchfile.txt and touchfile2.txt
  
  onfilechange.sh -s -w 10 -c "echo hello" /home/me/touchfile.txt
    watch touchfile.txt every 10 sec with stat and show "hello" on a change

#Test on command line

To make a test on commandline touch a testfile touch /tmp/mytestfile. The start the script with enabled debugging (-d) in a 2nd terminal:

/usr/local/bin/onfilechange.sh -c 'echo Changes!'“/tmp/mytestfile“

______________________________________________________________________________

  T R I G G E R    C O M M A N D    O N    A    F I L E C H A N G E   
_______________________________________________________________________| v1.06


--- summary
checking file(s): /tmp/mytestfile
with command [stat] 
with a sleep time of [5] seconds 
on change execute command [echo Changes!]

...............................................................................



>>>>> watched files
ls: cannot access '/tmp/mytestfile': No such file or directory
INFO: file '/tmp/mytestfile'  (or one of them) does not exist yet

>>>>> start
waiting for file changes ...

If you create the file in another terminal window touch /tmp/mytestfilethen you get the reaction:

>>>>> start
waiting for file changes ...
1c1
< stat: cannot statx '/tmp/mytestfile': No such file or directory
---
> regular empty file /tmp/mytestfile | perms: -rw-r--r--; user 1000 (axel) group 1000 (axel) | size: 0 byte | last modification 2025-01-17 13:39:02.543806368 +0100
>>>>> Fri Jan 17 13:39:06 CET 2025 Executing echo Changes! ...

The given command will be executed and its output is visible. Then it waits again.

Changes!
Command was successful.

>>>>> waiting for the next change ...

#Tipps and tricks

#Multiple files

You cannot watch just a single file but multiple files too. Just add all of them at the and of the command line as parameters.

onfilechange.sh -c <command> <FILE_1> <FILE_2> <FILE:N>

The files are seperated by spaces. If they contain spaces or other special chars you need to quote them or mask the special characters. Both of these examples are equal:

onfilechange.sh -c <command> "directory 1" "directory 2" 
onfilechange.sh -c <command>  directory\ 1  directory\ 2

#Run permanently

If the file watcher should run always ans always start after reboot, then create a service. In the chapter Service is an example for systemd.