spugbrap’s blog

I’ve never been a fan of using tabs to indent my code; I prefer spaces. Writing code is an art form, and when you use tabs to indent, you can’t assume that it will still look pretty on someone else’s machine, or in another application, etc., since tab sizes are platform-dependent and–although usually user-definable–the default size (typically 8 spaces, I think) tends to be much larger than my own 2-4 space indentation style.

However, some of my co-workers indent with tabs, and others indent with spaces. I’ve found that it’s easier for me to avoid inadvertently messing up existing code when I just bite the bullet and use tabs.

So, what follows are a couple of search/replace regular expressions I’ve recently used in TextPad, to make some existing code more consistent, by converting the spaces to tabs in certain relevant locations.

1. Regular expressions for aligning inline comments with tabs

Customization: The number 2, in curly braces (above), should be replaced with the number of spaces that are used for indentation, in the code you’re running this on. In this case, the code was indented in increments of 2 spaces. Sometimes I deal with code that’s indented in increments of 4 spaces, in which case that 2 would change to a 4.

Manner of execution: Run via Replace All, repeatedly, until there are no more matches.

Recommended scope: I used it on a very specific block of selected code. Keep reading for the specific format.

When I used this on a block of code that consisted of variable declarations and //-style comments, it ended up making the comment blocks all line up nicely. Here is an animated GIF¹ of a series of screenshots, showing how repeatedly running this expression transformed the comments into tab-indented comments that lined up nicely:

I’m not sure how useful this will be, in general, because I think I just kind of lucked out when I got the results that I did. I thought it was worth sharing, though, because it impressed me when it produced results that were better than I had actually envisioned. :)

Two important things to note are:

• The actual variable declarations (beginning of each line) were already indented with 1 tab.
• There were a consistent number of spaces between the semicolons ending the variable declarations, and the double slashes starting the comments. While this didn’t help them line up, as spaces, it did make things pretty when the spaces were replaced with tabs.

If you’d like, you can see what my TextPad Replace dialog looked like, so you can see things like which checkboxes are checked, etc. Also, please note that in my TextPad preferences, I have it set to Use POSIX regular expression syntax (as previously mentioned, in another TextPad search/replace expression entry, a couple years ago).

2. Regular expressions for changing leading indentation spaces to tabs

Customization: As with the first expression, above, the number in curly braces should be changed to the spacing increment used for indentation, in the code you’re running this on.

Manner of execution: Run via Replace All, repeatedly, until there are no more matches.

Recommended scope: It can be used on a block of selected text, the entire active document, or even on all open documents, if you’re brave and somewhat evil. :)

¹ Sorry for using an animated GIF. I’d rather not have something constantly flashing on the page, because it distracts, and resembles an advertisement. I would have preferred another solution, but I racked my brain for over two hours, trying to decide how to present this series of 9 screenshots. I didn’t want to alienate readers who might read this using a feed reader that doesn’t support javascript, and I hate making people click through from the feed to the main site–I strongly prefer full-text rss feeds! Laying the 9 images out horizontally or vertically took up either too much space, or required making the images too tiny to read. In the end, this animated GIF seemed like the best portable way to show the effect I was trying to show. I won’t make a habit of using them, though. :)

[return to top] / [expression 1] / [expression 2]

I’m a programmer, not a DBA, but I do have to be able to perform basic database configuration and maintenance tasks. One thing that’s come up, a couple times, over the past few years, is a transaction log getting full.

There are a couple of reasons this can happen:

• poorly written queries that run for a very long time
• applications neglecting to end transactions, when they encounter error conditions

Here are a few useful commands I’ve found that deal with transaction logs (Note: I’m using Sybase ASE 12.5.1):

check for long-running transactions (found here):
use master;

SELECT * FROM syslogshold
WHERE dbid = db_id(’MyDbName’);

transaction log space free:
SELECT CONVERT(CHAR,
(lct_admin('logsegment_freepages', 4) -
lct_admin('reserved_for_rollbacks', 4)) * 2)

transaction log space total:
SELECT SUM(size)
FROM master..sysusages
WHERE dbid = db_id('MyDbName')
AND segmap & 4 = 4 -- logsegment

dump the transaction log (clears it out, so things can get moving again!):
***WARNING*** Use this command at your OWN RISK! Please do some additional reading before executing the following statement, so that you fully understand the implications. The transaction log is there for a reason, and, from what I understand, you should not tamper with it unless you know what you’re doing. On the occasions that I’ve used this, it was a last resort. It solved my problems, with no ill effects, but it might not solve yours!

dump tran myDbName with truncate_only;
commit;

For additional information/reference, Sybase’s online books sometimes come in handy. When trying to find out how to dump transaction logs, I referred to their dump transaction page.

Another site I’ve found useful*, on numerous occasions, is Sybase 101. I found a related tip, there, for tips, there, for Dealing With Server Failure, which addresses what to do when your log fills up completely, such that you can’t even restart the server.

*Beware: I just noticed that Sybase 101 has become less useful than it used to be, because useful pages are automatically redirecting to one main start page. If they were just trying to prevent deep linking from the outside world, I could understand this behavior a little more; but it’s even happening when I click other links from their own site! Navigation works fine with javascript disabled, though.

I’m a big fan of cygwin, so most of the time I have countless small-but-useful utilities at my disposal, without having to think twice. But, when doing system administration on a client’s server in an off-site data center, I’m very limited in what software I’m allowed to put on the machine. For sysadmin tasks, though, unix utilities are pretty hard to do without.

For instance, one of my favorite tools for watching log files is tail, usually with a -f or -F parameter (”follow” and “follow+retry”, respectively; both let you see new lines as the file(s) grow, the latter keeps trying in case the file doesn’t exist yet). Unfortunately, vanilla Windows installations still don’t come with a tail utility. So, I went searching for other ways of tailing files, besides installing cygwin.

One method that I found can be used without any additional software. It’s just a batch file. It can’t follow changes, but you can at least view the last N lines of a file. Here it is, from a FAQ on Microsoft TechNet, by Jerold Schulman:

@echo off
if {%1}=={} @echo FileName parameter required.&goto :EOF
if not exist %1 @echo %1 does NOT exist.&goto :EOF
setlocal
set file=%1
set /a number=10
if not {%2}=={} set /a number=%2
for /f %%i in ('find /v /c "" ^< %file%') do set /a lines=%%i
@echo %lines% lines in file %file%.
if %number% GEQ %lines% set /a start=0&goto console
set /a start=%lines% - %number%
:console
more /e +%start% %file%
endlocal


I really missed tail -F, though, so I went looking again for some way to tail -F without cygwin. There are plenty of freely available utilities out there that should do the trick, but I wanted to find the simplest, safest one, from a trustworthy source, preferrably open-source so the integrity is verifyable. After looking at a couple open-source options, I stumbled across a page on malektips.com: Windows XP and DOS - Unix Style Tail Command

I learned from that page that you can download the Windows Server 2003 Resource Kit Tools package for free, and that it includes a tail utility (including -f functionality). After downloading and installing that on my laptop, I looked in the installation directory, and found tail.exe there. It’s only 7k!

Next, I FTP’d that to the server I needed to run it on, and gave it a try, hoping that it did not have dependencies that required installing the whole Resource Kit Tools package. As it turns out, it worked liked a charm! It’s nice and small, and arguably from a trustworthy source (Microsoft itself). Easier to justify than most of the other tools I was able to find, in case anyone ever questions my putting it on the server.

This is extremely simple, but it’s something that I always forget, and I’m always happy to find it in my text file of miscellaneous useful snippets:

SELECT @@version

This is a simple bash function that I use pretty often. It comes in handy when I’m navigating a tree of source code in a cygwin bash shell, and want to edit a file in TextPad. You can just put this line in your .bashrc file, and make sure the directory where TextPad.exe lives is in your $PATH environment variable:

function tp() { textpad $(cygpath --mixed $1) & }

This allows me to do things like:

$find . -name '*Foo*.java'

which returns results like:

./src/com/spugbrap/foo/bar/TestFooImpl.java
./servlet/com/spugbrap/baz/FooDispatcher.java

Then I can just copy one of those full (but relative) paths to the clipboard, and paste it into a command that looks like this:

$tp ./servlet/com/spugbrap/baz/FooDispatcher.java

Now, regardless of where the root of this relative path exists on the file system, it will open that file in TextPad.

The only limitation that I run into with this is that it only lets you specify one file to open. It could probably be modified to handle multiple files pretty easily, but this hasn’t bothered me enough to deal with yet.