src/cmd/INIT/package.sh: add install subcommand

This now allows easy installation via:
bin/package install DESTINATION_DIRECTORY [ COMMAND ... ]

Commands are installed in bin and share/man subdirectories.
If no command is specified, ksh and shcomp are assumed.

bin/package

@@ -106,7 +106,7 @@ command=${0##*/}
 case $(getopts '[-][123:xyz]' opt --xyz 2>/dev/null; echo 0$opt) in
 0123)	USAGE=$'
 [-?
-@(#)$Id: '$command$' (ksh 93u+m) 2022-07-25 $
+@(#)$Id: '$command$' (ksh 93u+m) 2022-08-01 $
 ]
 [-author?Glenn Fowler <gsf@research.att.com>]
 [-author?Contributors to https://github.com/ksh93/ksh]
@@ -193,7 +193,17 @@ case $(getopts '[-][123:xyz]' opt --xyz 2>/dev/null; echo 0$opt) in
                     release incompatibilities has for the most part been
                     futile.]
             }
-        [+install\b To be reimplemented.]
+        [+install\b [ \adest_dir\a ]] [ \acommand\a ... ]]?Install commands
+            from the \b$INSTALLROOT\b tree
+            into appropriate subdirectories of \adest_dir\a.
+            If \adest_dir\a does not exist,
+            then it and any necessary subdirectories are created.
+            \adest_dir\a can be a directory like \a/usr/local\a
+            to install the \acommand\as directly,
+            or a temporary directory like \a/tmp/pkgtree/usr\a
+            to prepare for packaging with operating system-specific tools.
+            If no \acommand\a is specified,
+            then \aksh\a and \ashcomp\a are assumed.]
         [+make\b [ \apackage\a ]] [ \aoption\a ... ]] [ \atarget\a ... ]]?Build
 	    and install. The default \atarget\a is \binstall\b, which makes
 	    and installs \apackage\a. If the standard output is a terminal
@@ -454,7 +464,14 @@ DESCRIPTION
                   similar, predictable style. OS point release information is
                   avoided as much as possible, but vendor resistance to release
                   incompatibilities has for the most part been futile.
-    install To be reimplemented.
+    install [ dest_dir ] [ command ... ]
+          Install commands from the $INSTALLROOT tree into appropriate
+          subdirectories of dest_dir. If dest_dir does not exist, then it and
+          any necessary subdirectories are created. dest_dir can be a directory
+          like /usr/local to install the commands directly, or a temporary
+          directory like /tmp/pkgtree/usr to prepare for packaging with
+          operating system-specific tools. If no command is specified, then ksh
+          and shcomp are assumed.
     make [ package ] [ option ... ] [ target ... ]
           Build and install. The default target is install, which makes and
           installs package. If the standard output is a terminal then the
@@ -535,7 +552,7 @@ SEE ALSO
   mamake(1), pax(1), pkgadd(1), pkgmk(1), rpm(1), sh(1), tar(1), optget(3)
 
 IMPLEMENTATION
-  version         package (ksh 93u+m) 2022-02-24
+  version         package (ksh 93u+m) 2022-08-01
   author          Glenn Fowler <gsf@research.att.com>
   author          Contributors to https://github.com/ksh93/ksh
   copyright       (c) 1994-2012 AT&T Intellectual Property
@@ -1705,6 +1722,14 @@ err_out()
 	exit 1
 }
 
+trace()
+(
+	PS4="${action}: executing: "
+	exec 2>&1  # trace to standard output
+	set -o xtrace
+	"$@"
+)
+
 # cc checks
 #
 #	CC: compiler base name name
@@ -2634,6 +2659,48 @@ make_recurse() # dir
 	done
 }
 
+do_install() # dir [ command ... ]
+{
+	cd "$INSTALLROOT"
+	printf 'install: installing from %s\n' "$PWD"
+	set -o errexit
+	dd=$1
+	shift
+	case $dd in
+	'' | [^/]*)
+		err_out "ERROR: destination directory '$dd' must begin with a /" ;;
+	esac
+	# commands to install by default
+	test "$#" -eq 0 && set -- ksh shcomp  # pty suid_exec
+	for f
+	do	test -f "bin/$f" || err_out "Not found: $f" "Build first? Run $0 make"
+	done
+	# set install directories
+	bindir=$dd/bin
+	mandir=$dd/share/man
+	man1dir=$mandir/man1
+	# and off we go
+	trace mkdir -p "$bindir" "$man1dir"
+	for f
+	do	# install executable
+		trace cp "bin/$f" "$bindir/"
+		# install manual
+		case $f in
+		ksh)	trace cp "$PACKAGEROOT/src/cmd/ksh93/sh.1" "$man1dir/ksh.1"
+			;;
+		*)	# AT&T --man, etc. is a glorified error message: writes to stderr and exits with status 2 :-/
+			manfile=$man1dir/${f##*/}.1
+			bin/ksh -c '"$@" 2>&1; exit 0' _ "bin/$f" --nroff >$manfile
+			# ...so we cannot check for success; instead, check the result.
+			if	grep -q '^.TH .* 1' "$manfile"
+			then	printf "install: wrote '%s --nroff' output into %s\n" "bin/$f" "$manfile"
+			else	rm "$manfile"
+			fi
+			;;
+		esac
+	done
+}
+
 # check for native ASCII 0:yes 1:no
 
 __isascii__=
@@ -2704,9 +2771,9 @@ export)	case $INSTALLROOT in
 	;;
 
 install)cd $PACKAGEROOT
-	echo "A proper installation command is coming back soon, sorry." >&2
-	echo "Meanwhile, copy ksh and shcomp from: $INSTALLROOT/arch/$HOSTTYPE/bin" >&2
-	exit 1
+	# TODO: breaks on directories with spaces or glob characters; make arguments handling robust
+	test -n "$args" || err_out "Usage: $0 install ROOTDIR [ COMMANDNAME ... ]"
+	capture do_install $args
 	;;
 
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