Create and document basic installation script

README.md

@@ -4,6 +4,35 @@ would-reformat - automatic reformatting for emacs without being annoying
 
 # Installation
 
+- Change to the directory where you would want to use **would-reformat**:
+  `$ cd ~/devel/my-project`
+- From that directory, call the script `install.sh` in the directory where
+  you have **would-reformat** checked out:
+  `you@host:~/devel/my-project $ ~/src/would-reformat/install.sh`
+
+This will do the following:
+
+- create the directory `~/devel/my-project/bin` if it does not exist
+- create `~/devel/my-project/_reformat-common.sh`,
+  `~/devel/my-project/do-reformat.sh`, and
+  `~/devel/my-project/bin/would-reformat.sh` as symlinks to files with
+  the same names in `~/src/would-reformat`.
+- create `~/devel/my-project/.dir-locals.el` as a symlink to the file
+  with the same name in `~/src/would-reformat`.
+
+This should work from a checkout wherever you happen to have it.  It doesn't
+need to be in `~/src`.  However, if you remove the checkout, then the symlinks
+will break, so don't do that.  If you rename the checkout, the symlinks will break.
+
+The directory `bin` with respect to `my-project` however is hardcoded
+(enhancements here are welcome).
+
+The script `install.sh` favors conservatism over being clever: for example,
+if it finds the file `~/devel/my-project/bin/do-reformat.sh` then it
+checks whether it is a symlink to `~/src/would-reformat/do-reformat.sh`.
+If it is not, then it just prints a warning rather than attempting to correct
+the situation.
+
 # Development
 
 

install.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+
+set -uo pipefail
+IFS=$'\n\t'
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+here=$(pwd)
+
+ret=0
+
+# If this use of readlink breaks, see
+# https://unix.stackexchange.com/questions/47710/find-only-destination-of-symlink
+# for discussion of alternatives.
+
+for i in _reformat-common.sh do-reformat.sh would-reformat.sh; do
+    if [[ -f "$here"/bin/"$i" ]] ; then
+        dest=$(readlink bin/$i)
+        if [[ x"$dest" == x"$DIR/$i" ]] ; then
+            echo $i is in place, good
+        else
+            echo $i exists but it is not a symlink or does not point to the right place
+            echo If it is a symlink, it points to: $dest
+            echo "(If it doesn't point anywhere, then it probably is not a symlink)"
+            ret=1
+        fi
+    else
+        # it doesn't exist; create it
+        echo setting $i up
+        mkdir -p $here/bin
+        ln -s $DIR/$i $here/bin/$i
+    fi
+done
+
+if [[ -f $here/.dir-locals.el ]] ; then
+    dest=$(readlink .dir-locals.el)
+    if [[ x"$dest" == x"$DIR/_dir-locals.el" ]] ; then
+        echo .dir-locals.el is in place, good
+    else
+        echo .dir-locals.el exists but it is not a symlink or does not point to
+        echo the right place
+        echo
+        echo It is possible that you are using .dir-locals.el for other purposes,
+        echo in which case this is not really an error.
+        ret=1
+    fi
+else
+    echo setting .dir-locals.el up
+    ln -s $DIR/_dir-locals.el $here/.dir-locals.el
+fi
+
+exit $ret