fswatch

fswatch is a developer tool that triggers commands in response to filesystem changes. Works well on Mac, Linux, and should also works on Windows(not well tested).

Install

go install github.com/codeskyblue/fswatch@latest

Simple way to use fswatch

Usage example

$ fswatch -v
3.0
$ fswtach --help
show help message ...

Watch file change event and trigger command

TODO: now only watch *.go, *.c, *.py files, watch depth = 0 (current directory)

$ fswatch sh -c "ls -l | wc -l"
fswatch >>> [] exec start: sh -c 'ls -l | wc -l'
       8
fswatch >>> [] finish in 11.822873ms
fswatch >>> changed: fswatch.go
fswatch >>> delay: 100ms
fswatch >>> [] exec start: [sh -c ls -l | wc -l]
       8
fswatch >>> [] finish in 13.606428ms
^Cfswatch >>> Catch signal interrupt!
fswatch >>> Kill all running ... Done

Hard way to use fswatch (not recommend)

Step 1

Create a config file fsw.yml

config file example though command fswatch with no arguments

desc: Auto generated by fswatch [fswatch]
triggers:
- pattens:
  - '**/*.go'
  - '**/*.c'
  # also support '!**/test_*.go'
  env:
    DEBUG: "1"
  # if shell is true, $cmd will be wrapped with `bash -c`
  shell: true
  cmd: go test -v
  delay: 100ms
  stop_timeout: 1s
  signal: "KILL"
  kill_signal: "SIGTERM"
watch_paths:
- .
watch_depth: 5

Step 2

Run fswatch directly. Every time you edit a file. Command go test -v will be called.

$ fswatch
fswatch >>> exec start: go test -v
# github.com/codeskyblue/fswatch
./fswatch.go:281: main redeclared in this block
	previous declaration at ./config.go:354
fswatch >>> program exited: exit status 2
fswatch >>> finish in 145.499911ms

support specify config file through fswatch --config myfsw.yml

You should know

How fswatch kill process

fswatch send signal to all process when restart. (mac and linux killed by pgid, windows by taskkill) Ctrl+C will trigger fswatch quit and kill all process it started.

Pattens

More about the pattens. The patten has the same rule like .gitignore. So you can write like this.

- pattens:
  - '*.go'
  - '!*_test.go'
  - '!**/bindata.go'

main.go changed will trigger command, but a_test.go and libs/bindata.go will be ignored.

FAQs

too many open files

For mac, run the following command

sysctl -w kern.maxfiles=20480
sysctl -w kern.maxfilesperproc=18000
ulimit -S -n 2048

reference

Other

Chinese Blog: http://my.oschina.net/goskyblue/blog/194240

Friendly link:

• bee
• fsnotify
• https://github.com/codeskyblue/kexec
• https://github.com/codeskyblue/dockerignore

Code History

I reviewed the first version of fswatch(which was taged 0.1). The code I look now is shit. So I deleted almost 80% code, And left some very useful functions.

Alternative

• https://github.com/cortesi/modd
• https://github.com/emcrisostomo/fswatch write with cpp
• https://github.com/Unknwon/bra Funny name.

LICENSE

Under MIT