Simplify install.sh (take 2) (#16829)

*  Simplify install.sh

* fix install.sh

* fix install.sh

* support installing to a file as well as a directory

* forgot to remove one line

* typos

* fix indentation

contrib/install.sh

@@ -15,14 +15,15 @@ done
 DEST=$1
 
 for SRC in $ARGS; do
-    # Copy file, then take output of the form 'src' -> 'dest' and get only 'dest'
-    DESTFILE=$(LC_ALL=C cp -va $SRC $DEST | sed -e $'s/ -> /\\\n/g' | tail -n 1)
+    cp -a $SRC $DEST
 
-    # If there are surrounding quotes, remove them.  We do this simply by knowing that the destination is always an absolute path
-    if [ "$(echo $DESTFILE | head -c1)" != "/" ]; then
-        DESTFILE=$(echo $DESTFILE | awk '{print substr($0, 2, length($0)-2)}')
+    if [ -d "$DEST" ]; then
+        DESTFILE="$DEST/$(basename "$SRC")"
+    else
+        DESTFILE="$DEST"
     fi
 
     # Do the chmod dance, and ignore errors on platforms that don't like setting permissions of symlinks
+    # TODO: Test if it's a symlink instead of having to redirect stderr to /dev/null
     chmod $PERMS $DESTFILE 2>/dev/null
 done