https://github.com/tomnomnom/symwatch

A tool to run a command when the target of a symlink changes
https://github.com/tomnomnom/symwatch

Last synced: 9 months ago
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A tool to run a command when the target of a symlink changes

• Host: GitHub
• URL: https://github.com/tomnomnom/symwatch
• Owner: tomnomnom
• License: mit
• Created: 2016-04-27T14:53:18.000Z (about 10 years ago)
• Default Branch: master
• Last Pushed: 2016-04-28T23:46:58.000Z (about 10 years ago)
• Last Synced: 2025-09-07T06:36:02.715Z (9 months ago)
• Language: Go
• Size: 9.77 KB
• Stars: 16
• Watchers: 2
• Forks: 3
• Open Issues: 2
• Metadata Files:
  • Readme: README.mkd
  • Changelog: CHANGELOG.mkd
  • Contributing: CONTRIBUTING.mkd
  • License: LICENSE

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README

          
# symwatch

Watches a symlink and runs a command when the target of the symlink changes.

[![Build Status](https://travis-ci.org/tomnomnom/symwatch.svg?branch=master)](https://travis-ci.org/tomnomnom/symwatch)

## Installation

```

go get github.com/tomnomnom/symwatch

```

## Usage

```

Usage:

  symwatch   []

Options:

  symlink	An absolute or relative path to a symlink

  command	The command to run when the symlink target changes

  pollInterval	The number of milliseconds to wait between polling the symlink (default 500)

Notes:

  * If the symlink is unreadable for more than 5 attempts the process will exit

  * Commands are passed to `sh -c`

Exit Codes:

  0	OK

  1	Invalid Arguments

  2	Invalid Symlink

  3	Symlink Went Away

Example:

  symwatch /var/www/current 'service apache2 graceful' 500

```

## Motivation

It's a fairly common pattern to use a symlink to point to the current version of

a codebase. Sometimes it's neccesary to restart processes or clear caches when the version

of a codebase changes.

## Why not use inotify?

It's not portable. In particular it does not work if the symlink being polled is on an NFS share.