X-Git-Url: https://git.ladys.computer/Shushe/blobdiff_plain/6773582e45aab385c96638fe9e90d811132a1005..12fbd559e25c8ac456254c4f4a69d53905045ef8:/README.markdown

diff --git a/README.markdown b/README.markdown
index 9523a8a..bf353e0 100644
--- a/README.markdown
+++ b/README.markdown
@@ -23,26 +23,10 @@ It makes things easier by :⁠—
 It aims to do this with zero dependencies beyond the programs already
   installed on your computer†.
 
-† The only non‐Posix programs‡ required (other than G·N·U Make itself,
-    and optionally Git) are those provided by `libxml2` and `libxslt`.
-On most operating systems, these libraries come pre·installed, but on
-  Linux machines the commandline utilities are often packaged
-  separately (as **`libxml2-utils`** and **`xsltproc`**), which may
-  still need to be installed.
-Additionally, not all Linux distributions bundle all necessary Posix
-  programs; on Debian (for example) you may need to separately install
-  **`sharutils`** for `uudecode` and `uuencode` and **`pax`** for
-  archiving.
-
-‡ This make·file also currently depends on non‐Posix `stat` but
-  attempts to handle both the G·N·U and B·S·D variants.
-It expects `xargs` to accept a `-0` option, which, while widely
-  supported, is not a part of the Posix standard.
-
-**Note:**
-⛩️📰 书社 requires functionality present in G·N·U Make 3.81 or later,
-  and will not work in previous versions, or with other implementations
-  of Make.
+† Assuming an operating system with a fairly featureful, and
+  Posix‐compliant, development setup (e·g, macOS).
+In fact, on Linux you will probably need to install a few programs:
+  `libxml2-utils`, `xsltproc`, `sharutils`, and `pax`.
 
 ## Nomenclature
 
@@ -64,6 +48,99 @@ The name <i lang="cmn-Hans">书社</i> was chosen to play on this pun, as
 In Ascii environments, ⛩️📰 书社 should be written `Shushe`, following
   the pinyin transliteration.
 
+## Prerequisites
+
+In most cases, ⛩️📰 书社 aims to require only functionality which is
+  present in all Posix‐compliant operating systems.
+There are a few exceptions.
+Details on particular programs are given below; if a program is not
+  listed, it is assumed that any Posix‐compliant implementation will
+  work.
+
+### `date`
+
+This is a Posix utility, but ⛩️📰 书社 currently depends on
+  unspecified behaviour.
+When the G·N·U version of `stat` is being used, then the G·N·U version
+  of `date` is also expected.
+
+### `file`
+
+This is a Posix utility, but ⛩️📰 书社 currently depends on
+  unspecified behaviour.
+It requires support for the following additional options :⁠—
+
+- **`-C`**, when supplied with `-m`, must be useable to compile a
+    `.mgc` magicfile for use with future invocations of `file`.
+
+- **`--files-from`** must be useable to provide a file that `file`
+    should read file·names from, and `-` must be useable in this
+    context to specify the standard input.
+
+- **`--mime-type`** must cause `file` to print the internet media type
+    of the file with no charset parameter.
+
+- **`--separator`** must be useable to set the separator that `file`
+    uses to separate file names from types.
+
+These options are implemented by the
+  [Fine Free File Command](https://darwinsys.com/file/), which is used
+  by most operating systems.
+
+### `git`
+
+This is not a Posix utility.
+Usage of `git` is optional, but recommended (and activated by default).
+To disable it, set `GIT=`.
+
+### `make`
+
+This is a Posix utility, but ⛩️📰 书社 currently depends on
+  unspecified behaviour.
+⛩️📰 书社 requires specifically the G·N·U version of `make`, and
+  depends on functionality present in version 3.81 or later.
+It is not expected to work in previous versions, or with other
+  implementations of Make.
+
+### `pax`
+
+This is a Posix utility, but not included in the Linux Standard Base or
+  installed by default in many distributions.
+Only `ustar` format support is required.
+
+### `stat`
+
+This is not a Posix utility, and nor is it particularly portable.
+To get around incompatibilities, ⛩️📰 书社 attempts to recognize G·N·U
+  `stat` by searching for the string `GNU` when invoked with the
+  `--version` option, and falls back to B·S·D behaviour otherwise.
+
+### `uudecode` and `uuencode`
+
+These are Posix utilities, but not included in the Linux Standard Base
+  or installed by default in many distributions.
+The G·N·U [Sharutils](https://www.gnu.org/software/sharutils/) package
+  can be installed to access them.
+
+### `xargs`
+
+This is a Posix utility, but ⛩️📰 书社 currently depends on
+  unspecified behaviour.
+It requires support for the `-0` flag, which must disable the special
+  quote and whitespace handling of `xargs` in favour of null‐terminated
+  strings.
+
+### `xmlcatalog` and `xmllint`
+
+These are not a Posix utilities.
+They is a part of `libxml2`, but may need to be installed separately
+  (e·g by the name `libxml2-utils`).
+
+### `xsltproc`
+
+This is not a Posix utility.
+It is a part of `libxslt`, but may need to be installed separately.
+
 ## Basic Usage
 
 Place source files in `sources/` and run `make install` to compile