$ cat >> $HGRCPATH << EOF

  > [extensions]

  > absorb=

  > EOF

  $ hg init repo1

  $ cd repo1

Make some commits:

  $ for i in 1 2 3; do

  >   echo $i >> a

  >   hg commit -A a -m "commit $i" -q

  > done

absorb --edit-lines will run the editor if filename is provided:

  $ hg absorb --edit-lines --apply-changes

  nothing applied

  [1]

  $ HGEDITOR=cat hg absorb --edit-lines --apply-changes a

  HG: editing a

  HG: "y" means the line to the right exists in the changeset to the top

  HG:

  HG: /---- 4ec16f85269a commit 1

  HG: |/--- 5c5f95224a50 commit 2

  HG: ||/-- 43f0a75bede7 commit 3

  HG: |||

      yyy : 1

       yy : 2

        y : 3

  nothing applied

  [1]

Edit the file using --edit-lines:

  $ cat > editortext << EOF

  >       y : a

  >      yy :  b

  >      y  : c

  >     yy  : d  

  >     y y : e

  >     y   : f

  >     yyy : g

  > EOF

  $ HGEDITOR='cat editortext >' hg absorb -q --edit-lines --apply-changes a

  $ hg cat -r 0 a

  d  

  e

  f

  g

  $ hg cat -r 1 a

   b

  c

  d  

  g

  $ hg cat -r 2 a

  a

   b

  e

  g