Andrew Beaton :: FAQ » Andrew

Grep to find ^M (Windows carriage return)

Andrew — Wed, 13 Jul 2011 16:58:17 +0000

There are two options here, one we used before when searching for the ^M’s in VI, the other is new:

^M

$'\r'

So to find all files with the Windows carriage return in them, use one of the following…

grep -r "^M" *

grep -r $'\r' *

^M is entered by pressing Ctrl+V followed by Ctrl+M

List and Install Security Updates via YUM

Andrew — Fri, 08 Jul 2011 17:04:30 +0000

You can now easily find out what security updates there are for your system (RHEL / CentOs / Fedora) by installing the ‘yum-security‘ plugin.

# yum install yum-security

To list available updates and see the relevant advisory code, use the following command:

# yum list security

To obtain information on the returned advisory codes, use the following:

# yum info-security

To list updates that are security relevent, use the following:

# yum --security check-update

And finally, to install only the security update packages, use the following:

# yum update --security

Add a program to start on LXDE startup

Andrew — Fri, 08 Jul 2011 16:33:22 +0000

If you need to get a program to start every time you boot into LXDE, you simply need to add it to the startup file here:

/etc/xdg/lxsession/LXDE/autostart

Add a line at the bottom of the file with the @ symbol and the program to run, for example:

@conky -c ~/.conky/.conkyrc.main &

View output of the dd command

Andrew — Thu, 23 Jun 2011 10:48:36 +0000

Recently whilst wiping some old hard disks I thought it would be useful to see what the ‘dd’ command was doing, rather than sitting there blankly for hour. I knocked up a little bash script to run in another terminal that will update the terminal running dd with some useful status information.

In this example, dd will be run as…

$ dd if=/dev/random of=/dev/sda

copy the following into ddUpdate.sh for example and run it…

#!/bin/sh ddpid=`ps auwx | awk '/dd if/ && !/awk/ { print $2}'` while [ "$ddpid" != "" ] do kill -USR1 $ddpid sleep 1 ddpid=`ps auwx | awk '/dd if/ && !/awk/ { print $2}'` done

This outputs the following to the terminal running dd…

xxxxxx records in xxxxxx records out xxxxxx bytes (xx nn) copied, xxxx s, xx MB/s

Get DateTime in YYYY-mm-dd HH:MM:SS format using Perl

Andrew — Thu, 14 Apr 2011 11:54:34 +0000

For many years I’ve been using the long process of obtaining everything from localtime(), adding 1900 to the year etc. etc. but I’ve just come across the method below, which uses strftime from the POSIX module.

use POSIX; my $DateTime = strftime "%F %T", localtime $^T;

This gives you:

2006-10-02 02:06:07

Now that’s a lot easier!

List stored procedures in PostgreSql

Andrew — Fri, 19 Nov 2010 22:03:20 +0000

This can be performed with the following command:

select proname from pg_proc where proowner <> [postgres usesysid];

where [postgres usesysid] comes from the pg_user table.

Remove ^M character with VI

Andrew — Wed, 10 Nov 2010 21:54:36 +0000

To remove ^M’s from a file, type the following:

:%s/[ctrlkey+v and ctrl-key+M]//g

The actual command is:

:%s/^V^M//g

“Object reference not set to an instance of an object.” when using OpenSubKey

Andrew — Tue, 09 Nov 2010 20:17:37 +0000

Whilst using a working project on my new development machine, I came across an issue that stumped me for a while.

Microsoft.Win32.Registry.LocalMachine.OpenSubKey(“subkey”).GetValue(“blah”) was failing with the error above, even though it worked perfectly previously and the key was clearly in the registry.

After a bit of research I found it to be because I’m now using a 64 bit version of Windows. Even though the key existed in HKEY_LOCAL_MACHINE\SOFTWARE\, it did not exist in HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\

To fix this, I simply created a copy of the key in Wow6432Node.

This may not be the correct solution but it worked for me…

MySQL error /usr/libexec/mysqld: unknown option ‘skip-bdb’

Andrew — Fri, 01 Oct 2010 11:29:00 +0000

MySQL version x is failing to start after upgrade with the following error:

/usr/libexec/mysqld: unknown option ‘—skip-bdb’

To fix comment out the following line in your my.cnf file:

#skip-bdb

You should now be able to restart MySQL

Postfix Mail Queue Commands

Andrew — Wed, 10 Mar 2010 21:03:58 +0000

To resend the mails in the mail queue, type either of the following two commands:

# postfix flush

# postfix -f

To see the mail queue, type:

# mailq

To remove all mail from the mail queue, type:

# postsuper -d ALL

To remove all mails in the deferred mail queue, type:

# postsuper -d ALL deferred