From 604fd85578b9b7ee9f0d994be4d0e14e03b9ef26 Mon Sep 17 00:00:00 2001
From: crc <crc@noemail.net>
Date: Tue, 14 May 2019 11:11:15 +0000
Subject: [PATCH] new example: unix-does-user-exist.forth

FossilOrigin-Name: ae18d3be928709883496d7a686d2717b0d9d42625fadc543d43509d787883568
---
 RELEASE_NOTES.md                   |  2 ++
 example/unix-does-user-exist.forth | 38 ++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 example/unix-does-user-exist.forth

diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 0a2e559..9e64c4c 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -39,6 +39,8 @@ July - September window for this release.
 - add mandelbrot.forth
 - add shell.forth
 - add sqlite3 wrapper
+- add unix-does-user-exist.forth
+- improved 99bottles.forth
 - corrected an issue in mail.forth
 - cleanup publish-examples.forth
 - publish-examples.forth now uses `retro-document` to generate glossaries
diff --git a/example/unix-does-user-exist.forth b/example/unix-does-user-exist.forth
new file mode 100644
index 0000000..a64509a
--- /dev/null
+++ b/example/unix-does-user-exist.forth
@@ -0,0 +1,38 @@
+This implements a word to determine if a user exists. This is done by
+parsing the results of `finger`.
+
+~~~
+:pipe>  (s-s)  file:R unix:popen [ file:read-line ] [ unix:pclose ] bi ;
+
+{{
+  :command  'finger_%s_2>&1 s:format ;
+  :parse    ASCII:SPACE s:tokenize ;
+  :login?   #0 a:th fetch 'Login: s:eq? ;
+---reveal---
+  :user:exists? (s-f)
+    &Heap [ command pipe> parse login? ] v:preserve ;
+}}
+
+'crc user:exists?
+'fakeuser user:exists?
+'root user:exists?
+~~~
+
+A second way is to parse the `/etc/passwd` file.
+
+~~~
+{{
+  :setup  (s-fs)    FALSE swap ': s:append s:keep ;
+  :match? (fss-fsf) over s:begins-with? ;  
+  :found  (fs-fs)   drop-pair TRUE s:empty s:keep ;
+  :check  (fss-fs)  match? [ found ] if ;
+  :seek   (fs-fs)   '/etc/passwd [ check ] file:for-each-line ;
+---reveal---
+  :user:exists? (s-f)
+    &Heap [ setup seek drop ] v:preserve ;
+}}
+
+'crc user:exists?
+'fakeuser user:exists?
+'root user:exists?
+~~~