gpm: A C repository from nsandman

#GPM: Generic Package Manager

This is a lightweight package manager designed to be easy to use and easy to make packages for. It is inspired by Homebrew, but is different in many regards:

Packages are JSON files with one URL and bash commands, not Ruby scripts with methods.
Packages are stored online, and you do not have to fork it to add custom packages.
GPM is written in C, not Ruby.
GPM modifies your $PATH variable instead of symlinking all installs.
Oh yeah, and it's cross-platform.

##Installation An install script will be available when GPM is in usable condition. If you want to see how it works, I compile it with this command:

gcc main.c json.c -std=c1x -lcurl -o gpm

I use Homebrew GCC 4.9 on Mac, but clang will work as well.

##Behind-the-Scenes Magic GPM creates a folder in your home directory called .gpm. This is its structure:

.gpm
 +-- installed
 |   +-- _installed.gpi
 |   +-- *anything else installed*
 +-- tmp

The "installed" folder is the actual directory that gets added to your PATH. All packages installed by GPM go here.

Finally, there is an empty directory called "tmp". As you can imagine, this is where all the temporary files go when installing a new package.

##Usage Using GPM is relatively simple.

Note: The first letter of most of these commands will work (eg gpm i [package]). This is helpful for quick typing and scripting.

####Installing

gpm install [package] [package2]

####Removing

gpm remove [package] [package2]

####Check if Package(s) Installed

gpm check [package] [package2]

####List Installed Packages

gpm list

####Get Package Info

gpm about [package][package2]

##FAQ ###So why is it "generic"? I dunno. The name "GPM" just sounds cool to me. I guess you could say because it installs packages that are not not for specific languages or environments (unlike npm, pip, etc.).

###Huh. So how do I make my own package? Easy! A simple package called "testing" (which, when run, echoes the word "testing" back.) would look like this:

{
	"url": "http://links.bargonaut.com/gpm/testing",
	"default": [
		"chmod +x {FILENAME}"
	],
	"win32": [
		"icacls {FILENAME} /grant Everyone:rx"
	]
}

Looks simple enough. Let's break this down.

GPM will first download the file in the URL. Then, it will run the commands in the "default" array on most systems, but using the "win32" array on Windows. If no "win32" is there, Windows will run the "default" commands. GPM will give you access to two variables:

{FILENAME}: This is the path to the file downloaded from the URL.
{GPMDIR}: This is the path to the GPM installation directory. This is usually ~/.gpm.

Let's write a slightly more complex one. This downloads and installs node.js:

{
	"url": "https://semver.io/node/stable",
	"default": [
		"echo \"Downloading latest node.js source...\"",
		"curl --progress-bar http://nodejs.org/dist/v`cat {FILENAME}`/node-v`cat {FILENAME}`.tar.gz > {GPMDIR}/tmp/node.tgz ",
		"echo \"Extracting...\"",
		"tar -xf {GPMDIR}/tmp/node.tgz -C {GPMDIR}/tmp",
		"echo \"Done. Building (be patient!)...\"",
		"{GPMDIR}/tmp/node-v`cat {FILENAME}`/configure --prefix={GPMDIR}/installed",
		"make -C {GPMDIR}/tmp/node-v`cat {FILENAME}`",
		"make -C install {GPMDIR}/tmp/node-v`cat {FILENAME}`",
		"rm {FILENAME}"
	]
}

It looks like a lot, but don't be daunted. Remove all the "echo" commands and it's easier to make sense of:

{
	"url": "https://semver.io/node/stable",
	"default": [
		"curl --progress-bar http://nodejs.org/dist/v`cat {FILENAME}`/node-v`cat {FILENAME}`.tar.gz > {GPMDIR}/tmp/node.tgz ",
		"tar -xf {GPMDIR}/tmp/node.tgz -C {GPMDIR}/tmp",
		"{GPMDIR}/tmp/node-v`cat {FILENAME}`/configure --prefix={GPMDIR}/installed",
		"make -C {GPMDIR}/tmp/node-v`cat {FILENAME}`",
		"make -C install {GPMDIR}/tmp/node-v`cat {FILENAME}`",
		"rm {FILENAME}"
	]
}

Okay, that's easier to read. Now let's look at this. It downloads the latest node version from http://www.semver.io. This is in the "url" field. So everywhere it says `cat {FILENAME}`, it's just putting the latest node.js version. So, assuming that's 0.12.2, this will be read as:

{
	"url": "https://semver.io/node/stable",
	"default": [
		"curl --progress-bar http://nodejs.org/dist/v0.12.2/node-v0.12.2.tar.gz > {GPMDIR}/tmp/node.tgz ",
		"tar -xf {GPMDIR}/tmp/node.tgz -C {GPMDIR}/tmp",
		"{GPMDIR}/tmp/node-v0.12.2/configure --prefix={GPMDIR}/installed",
		"make -C {GPMDIR}/tmp/node-v0.12.2",
		"make -C install {GPMDIR}/tmp/node-v0.12.2",
		"rm {FILENAME}"
	]
}

So it is now more obvious. All this script does is download the source, extract it, and run "./configure", "make", and "make install" with a few custom options.

nsandman/gpm