Apt ‘MMap ran out of room’ errors

Posted on February 28th, 2009 in General,Linux System Administration by Brandon

I’m seeing this problem more and more frequently when running apt-get or apt-cache commands. It seems to get most of the way through updating itself and then dies with this error:

E: Dynamic MMap ran out of room
E: Error occured while processing rapidsvn (NewVersion1)
E: Problem with MergeList /var/state/apt/lists/something_repodata_primary.xml
E: The package lists or status file could not be parsed or opened.

My understanding is that apt is running of some cache space and quits. I think this is referring to some memory limit, but am not sure (if anybody has a better explanation of the actual problem, please comment).

The fix is easy enough. Just create a file named /etc/apt/apt.conf.d/local.conf with this line:

APT::Cache-Limit 50000000;

That raises the limit from the default (I believe 8Mb) to 50Mb and has worked well for me.

CSV from the MySQL Command Line

Posted on February 18th, 2009 in General,Linux System Administration,MySQL by Brandon

I frequently need to generate a quick report generated from a quick database query. I have been doing this by creating a simple PHP script that queries the database and then displays the results as a CSV. However, I just found a way to do it directly from the MySQL command line, which makes it possible to skip the steps of creating the PHP script.

Simply run the command like this:

mysql>SELECT * FROM sometable INTO OUTFILE '/tmp/output.csv'
   FIELDS TERMINATED BY ',';

That will save the results to the file specified in a simple CSV format. There are also options for enclosing fields in quotes, the line terminators, and several other options.

It is now 1234567890

Posted on February 13th, 2009 in General,Linux System Administration by Brandon

It went by without much fanfare:

[root@dev ~]# date +%s
1234567890

Good Email Obfuscator

Posted on February 9th, 2009 in General by Brandon

I usually avoid putting mailto links on websites because they are easily scraped by spammers and fed into spam lists. But sometimes it is just necessary to have one. There are ways of encoding email addresses using javascript or special HTML characters that make it more difficult for spammers to see the email addresses.

I’ve done the encoding on my own for a while, but just found this Email Obfuscator that does a good job of it, so I’ll be using that form now on.

SSH Error: trying to get more bytes 4 than in buffer 0

Posted on February 6th, 2009 in General,Linux System Administration by Brandon

I ran across this cryptic error message in an SSH log file today:

Feb  7 03:33:21 hostname sshd[19439]: error: buffer_get_ret: trying to get more bytes 4 than in buffer 0
Feb  7 03:33:21 hostname sshd[19439]: fatal: buffer_get_int: buffer error

The problem is actually a corrupt line in a users ~/.ssh/authorized_keys file. This user had copy/pasted a new key into his authorized_keys file and it had a newline after the ssh-rsa. Strangely enough, people were still able to authenticate if their key was above the corrupted line. Users whose key was listed below the corrupt line were not able to log in.

PHP 5.1 Doesn’t have timezone_identifiers_list() by default

Posted on February 5th, 2009 in General,PHP by Brandon

According to the PHP documentation for timezone_identifiers_list(), that function should be included in PHP 5.1.x. The note on DateTime installation mentions, however, that it was only experimental support, and had to be compiled specifically to support it.

The fix, then, is to recompile PHP 5.1.x with

CFLAGS=-DEXPERIMENTAL_DATE_SUPPORT=1

or to upgrade to PHP 5.2 where it is enabled by default.

My particular problem surfaced with some Drupal code that required the function.