SSDs are the way to go!

I bought an intel X25-M SSD last week and it does make a *big* difference! It is faster, develops less noise and heat and the battery lasts longer.

I am using it with a lenovo thinkpad t410 laptop running Ubuntu 10.10 and it’s just great!

For what it’s worth I am running a pretty recent kernel in conjunction with the Ubuntu maverick userland. Not sure how well the normal 2.6.35 kernel supports SSDs.

Anyway, SSDs are the way to go :-)

Combining ack-grep and xargs

Gotta love the command line..

I use ack-grep a lot and really, really like it. Kudos to the author and to the maintainer who takes care of the ubuntu package :-)

Sometimes though I was missing grep‘s --exclude feature that allows me to ignore certain paths while searching.

There are occasions where I e.g. want to see calls to a certain function in the code base but I am not interested in tests. Today I found an (embarrassingly) easy way to get that behaviour using xargs:

$ find . -name \*.py | grep -v tests/ | xargs ack-grep -C 3 -w 'Message\('

The snippet above first accumulates the paths of interests, then filters them and finally lets ack-grep loose on them.

Ta-da! There you go :-)

Handy bash function for merge conflicts

I have been merging packages from debian unstable to ubuntu karmic lately and every so often I need to look at a merge conflict.

Sometimes it’s not so obvious why a conflict occurred at all. Here’s an example conflict from the libsepol package:

  1 <<<<<<< libsepol-2.0.32-1ubuntu1 (ubuntu)
  3     /* Get the scope info for this boolean to see if this is the declaration,
  4      * if so set the state */
  5     scope = hashtab_search(state->cur->policy->p_bools_scope.table, id);
  6     if (!scope)
  7         return SEPOL_ERR;
  8     if (scope->scope == SCOPE_DECL)
  9         base_bool->state = booldatum->state;
 10 
 11 =======
 13     /* Get the scope info for this boolean to see if this is the declaration,
 14      * if so set the state */
 15     scope = hashtab_search(state->cur->policy->p_bools_scope.table, id);
 16     if (!scope)
 17         return SEPOL_ERR;
 18     if (scope->scope == SCOPE_DECL)
 19         base_bool->state = booldatum->state;
 20 
 21 >>>>>>> libsepol-2.0.36-1 (debian)

In order to avoid staring at the screen until my eyes start to bleed :) I came up with the following bash function:

  1 function dsec() {
  2     xclip -selection clipboard -o > /tmp/patch-seg-to-diff.txt
  3     rm -f /tmp/ubuntu-snippet.txt /tmp/debian-snippet.txt
  4     ed /tmp/patch-seg-to-diff.txt > /dev/null 2>&1 <<-EOUBUNTU
  5         1 d
  6         /^===/,$ d
  7         wq /tmp/ubuntu-snippet.txt
  8 EOUBUNTU
  9     ed /tmp/patch-seg-to-diff.txt > /dev/null 2>&1 <<-EODEBIAN
 10         1,/^===/d
 11         $ d
 12         wq /tmp/debian-snippet.txt
 13 EODEBIAN
 14     echo 'diff -Nru /tmp/ubuntu-snippet.txt /tmp/debian-snippet.txt | colordiff | less'
 15     diff -Nru /tmp/ubuntu-snippet.txt /tmp/debian-snippet.txt | colordiff | less
 16 }

I can now use my favourite editor to copy the conflicting code to the clipboard. When invoked on the command line the dsec function reads the clipboard content and chops it apart (using the ed utility) into a debian and an ubuntu snippet respectively. Subsequently it invokes the diff utility on the two snippets showing me how they differ.

 1 --- /tmp/ubuntu-snippet.txt 2009-06-26 12:42:04.000000000 +0200
 2 +++ /tmp/debian-snippet.txt 2009-06-26 12:42:04.000000000 +0200
 3 @@ -1,5 +1,5 @@
 4     /* Get the scope info for this boolean to see if this is the declaration,
 5 -    * if so set the state */
 6 +    * if so set the state */
 7     scope = hashtab_search(state->cur->policy->p_bools_scope.table, id);
 8     if (!scope)
 9         return SEPOL_ERR;

Hmm .. this looks like a white space issue. Since the dsec function printed the actual diff command to the terminal, I can copy and paste that to the command line and add the -b parameter so that the diff utility ignores changes in the amount of white space and ..

 1 $ diff -Nrub /tmp/ubuntu-snippet.txt /tmp/debian-snippet.txt
 2 $ echo $?
 3 0

.. voila! the diff output this time around is empty.

In order for this to work the utilities used must be installed, so e.g. on a ubuntu system run:

sudo apt-get install xclip colordiff

And .. don't forget to have fun :)