Entr: trying to trigger function while monitoring file change about entr HOT 12 CLOSED

I am having a similar question, but I don't really like the solution provided in this thread so far, maybe it's because I am running multiple entr processes without while loop.
Then I figured out another solution by creating a second shell script and source it. Hope it can help others.

file utils.sh:

do_it() { echo it; }
do_that() { echo that; }

file run.sh:

ls folder1/* | entr sh -c 'source utils.sh; do_it' &
ls folder2/* | entr sh -c 'source utils.sh; do_that'

from entr.

The problem there is that the function you defined is local to your current shell, so it cannot be run by external commands

$ do_it(){ echo Eita!; }
$ /usr/bin/time do_it
time: do_it: No such file or directory
        0.00 real         0.00 user         0.00 sys
$ /bin/sh -c 'do_it'
sh: do_it: not found

from entr.

This code works, look:

while inotifywait -e close_write folder1/* folder2/*; do do_it; done

Even if I write:

export -f do_it

I got as a return: "entr: exec do_it: No such file or directory".

I think it has something to be with the use of "exec" by entr... Does it make sense? The error "exec...: No such file or directory" is not exclusive of entr.

from entr.

A function can be exported to a subshell, but you cannot execute a function with an external program. If you want to execute shell functions, you can write a loop such as this

#!/bin/sh

do_it(){ echo 'Eita!'; }

while true; do
    do_it
    ls folder1/* folder2/* | entr -pd -s 'kill $PPID'
done

(entr doesn't have a "one-shot" option, so kill $PPID is used to terminate itself when a file changes)

from entr.

Okay, I got it. Now, is there a way to run the function after entr is called? I tried:

entr -pd -s 'kill $PPID' && do_it

entr -pd -s 'kill $PPID' & do_it

entr -pd -s 'kill $PPID' ; do_it

but none of these worked...

from entr.

& will background the process, and && will run only on exit code 0 so that's not what you want. The last option you listed should work

entr -pd -s 'kill $PPID' ; do_it

is equivalent to

entr -pd -s 'kill $PPID'
do_it

Running the shell with set -x might help debug this

from entr.

Thank you very much.

It enters a loop:

entr -pd -s 'kill $PPID' ; do_it
entr: cannot create kqueue: Too many open files

from entr.

How many files are under the directories you're piping into entr? Also what is the open file limit (ulimit -n)?

here are the instructions for raising the max number of open files:

http://eradman.com/entrproject/limits.html

from entr.

How many files are under the directories you're piping into entr?
Files for an normal EPUB file. No more than 100.

ulimit -n
1024

I noticed that inotify was returning the same error. So I restart Ubuntu and then all is running fine.

If there is anything I can do to you, just say it. Thank you very much.

from entr.

Super! Glad it's working for you.

from entr.

A function can be exported to a subshell, but you cannot execute a function with an external program. If you want to execute shell functions, you can write a loop such as this

#!/bin/sh

do_it(){ echo 'Eita!'; }

while true; do
    do_it
    ls folder1/* folder2/* | entr -pd -s 'kill $PPID'
done

(entr doesn't have a "one-shot" option, so kill $PPID is used to terminate itself when a file changes)

@eradman This code won't exit with ctrl+c, is there a workaround to this??

from entr.

@OliverBrotchie, since 4.5 entr does have a one-shot option: -z.

I bet ctrl-c doesn't work because the shell loop doesn't give you time to interrupt it. Try replacing true with sleep

#!/bin/sh

do_it(){ echo 'Eita!'; }

while sleep 0.1; do
    do_it
    ls folder1/* folder2/* | entr -pdz echo "reloading"
done

from entr.