# how.sh



takes a package name, a version, and a path.  mounts scripts for patching,

configuring, building, and installing the given version of the package at the

given path in read-only mode using either overlayfs or, if no package-specific

scripts were found, a bind mount.



dependencies: `shsort` and `vercmp`, as well as 'how-defaults' and 'how-pkgs'

repositories.  (see makefile.)



55 SLOC.



usage: how <package> <version> <path>



## package structure



if a package or version is not recognized, how.sh will bind-mount the `default`

directory in read-only mode at the requested path.  a package and version is

recognized based on the presence of a subdirectory in the `pkg` directory

matching the package name with a subdirectory whose name translates to a version

equal to or less than version of the package requested, or a subdirectory named

`default`.  the structure looks something like this:



    pkg/

    |-- <package>/

    |   |-- <version>/

    ...



`version` is matched using `vercmp`.  if `vercmp` has a format that matches the

package name, then that format is used to compare versions for the package.

otherwise, the default comparison function is used.



the version directories are sorted using `shsort` and `vercmp` and mounted as an

overlay filesystem with the lower versions being lower in the overlay and higher

versions being higher.  `default` package subdirectories are always one layer

above the `default` directory;  the `default` directory is always lowest.



## patches



multiple patches may be offered in a package.  by convention, patches are kept

in the `patches` subdirectory of the package root.  the default `patch` command

looks for a single combined patch, likely constructed by concatenating or

otherwise combining offered patches, under the filename `patch` in the package

root.