commit 4c2a91533d1ba44ea50e1e870fefc03723dec3ba
Author: yafox <yafox@box>
Date:   Tue Nov 24 20:54:17 2020 +0000

    initial commit

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..bd8c239
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright 2020 "yafox"
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/README b/README
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--- /dev/null
+++ b/README
@@ -0,0 +1,36 @@
+shsort
+======
+
+a recursive quicksort in pure posix shell script using any arbitrary function
+or command capable of parsing a comparison expression and outputing "yes" or
+"no."  (e.g., anything that takes a string in the form of "1 > 3" as a command
+line argument and echoes "no" and takes "1 < 3" and echoes "yes".)
+
+34 SLOC.
+
+usage: shsort [-r] <comparator command> [<list>]
+
+shsort expects a newline delimited list of elements to sort.  the list may be
+passed via stdin in or on the command line as the <list> argument.
+
+the comparator command is used as-is and may be a string including flags.
+
+for example:
+
+    $ printf "2.9\n1.2\n3.4\n2.1\n2.1-rc0\n2.12" | shsort "vercmp -f default"
+    3.4
+    2.12
+    2.9
+    2.1
+    2.1-rc0
+    1.2
+
+`-r` reverses the sort order:
+
+    $ printf "2.9\n1.2\n3.4\n2.1\n2.1-rc0\n2.12" | shsort -r "vercmp -f default"
+    1.2
+    2.1-rc0
+    2.1
+    2.9
+    2.12
+    3.4
diff --git a/makefile b/makefile
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--- /dev/null
+++ b/makefile
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+SRCDIR = $(dir $(realpath $(firstword $(MAKEFILE_LIST))))
+PREFIX ?= /usr
+DESTDIR ?= $(PREFIX)/bin
+
+install:
+	cp -a $(SRCDIR)/shsort.sh $(DESTDIR)/shsort
+
+uninstall:
+	rm $(DESTDIR)/shsort
diff --git a/shsort.sh b/shsort.sh
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--- /dev/null
+++ b/shsort.sh
@@ -0,0 +1,46 @@
+#!/bin/sh
+
+set -e
+
+usage() { echo "usage: shsort [-r] <comparator> [<list>]" >&2 && exit 0; }
+
+[ "$1" ] || usage
+
+[ "$1" != "-r" ] || { rev="yes" && shift; }
+
+cmpfn="$1"
+shift
+
+quicksort() {
+    len="$(printf "$@\n" | wc -l)"
+    [ "$len" -gt 1 ] || { echo "$@" && return 0; }
+
+    pvtidx="$(expr $len / 2)"
+    pvt="$(printf "$@\n" | head -n$pvtidx | tail -n1)"
+
+    parted="$(printf "$@\n" | while read elem; do
+        { [ "$elem" ] && [ "$elem" != "$pvt" ]; } || continue
+        [ "$($cmpfn "$elem < $pvt")" = "yes" ] \
+        && printf "<\t$elem\n" \
+        || printf ">\t$elem\n"
+    done)"
+    lesser="$(printf "$parted\n" | grep "^<" | cut -f2)"
+    greater="$(printf "$parted\n" | grep "^>" | cut -f2)"
+
+    if [ "$rev" ]; then
+        printf "%s\n%s\n%s\n" "$(quicksort "$lesser")" "$pvt" "$(quicksort "$greater")"
+    else
+        printf "%s\n%s\n%s\n" "$(quicksort "$greater")" "$pvt" "$(quicksort "$lesser")"
+    fi
+}
+
+if [ "$@" ]; then
+    elems="$@"
+else
+    while read input; do
+        elems="$elems$input\n"
+    done
+fi
+[ "$elems" ] || usage
+
+quicksort "$elems" | sed '/^$/d'
diff --git a/sloc.sh b/sloc.sh
new file mode 100755
index 0000000..0129927
--- /dev/null
+++ b/sloc.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+# strip all trailing whitespace, then all leading whitespace, then all lines
+# starting with '#', then all empty lines. then count the remaining lines.
+sed 's/[[:space:]]*$//g; s/^[[:space:]]*//g; s/^#.*$//g; /^$/d' shsort.sh \
+| wc -l - \
+| cut -d' ' -f1
+
+# note that this script's ELOC is NOT included in the count.