Linux / Unix Tips and Tricks

Using rsync to synchronize a filesystem

len — Wed, 27 May 2009 09:16:30 +0200

Here's the command that I use to synchronize a filesystem from one server to another:

rsync -avx --numeric-ids --progress --delete 10.0.0.1:/mnt/sda1/ /mnt/sda1/

The -a option sets “archive mode”, which essentially turns on a number of rsync options 
that preserve file ownership and permissions and other settings. 
The -v option makes rsync provide more output about what it is doing, 
and the --progress argument displays a progress meter so you can keep up with how long rsync will take.

The other two arguments are rather important, and if you don't
use rsync regularly, you might not come across them much. The -x argument
tells rsync to stick to one filesystem. This is important particularly
when you back up the / partition; otherwise, rsync happily will traverse
into /home or any other partitions you have and copy them all into your
local /mnt/sda1 mountpoint, which probably will not have enough space
to hold everything. The --numeric-ids argument sets file permissions
on the destination files based on their numeric ID and not the matching
user or group name.

TT Assen 2009

len — Sat, 03 Jan 2009 19:36:02 +0100

Zaterdag 27 juni 2009 is het weer zover !!! Dan doet het MotoGP circus Assen aan en wij zijn er bij !

bevestigd niet bevestigd

Nr	Zitplaats	Wie	Met de motor	Vanuit
1.	DS-16-1	Joram Betgen	JA	Almere
2.	DS-16-2	Benjamin	Achterop bij Len	Zeewolde
3.	DS-16-3	Henny	JA	Zeewolde
4.	DS-16-4	Henny	JA	Zeewolde
5.	DS-16-5	Henny	JA	Zeewolde
6.	DS-16-6	Henny	JA	Zeewolde
7.	DS-16-7	Len Kranendonk	JA	Zeewolde
8.	DS-17-1	Martijn van Leeuwen	JA	Vleuten
9.	DS-17-2	Michel van Tuijl	JA	IJsselstein
10.	DS-17-3	Wout Kohler	JA	Vleuten
11.	DS-17-4	Arjan Jongsma	JA	Zuidwolde
12.	DS-17-5	Bert Lambregts	NEE	Bunschoten
13.	DS-17-6	Bert Lambregts	NEE	Bunschoten
14.	DS-17-7	Bert Lambregts	NEE	Bunschoten

Ook dit jaar hebben we weer superplaatsen weten te bemachtigen op de Strubben tribune, die nu (begin januari) al uitverkocht is.

Solaris 10: Enable Samba for Windows File Sharing

len — Tue, 23 Dec 2008 09:44:10 +0100

Today I got a question about users that want to access some FIX logfiles on a Solaris 10 server.
Of course you can give them (restricted) ssh access so they could access the files using WinSCP,
but I thought it would be easier to enable SAMBA for them so they could access the logfiles using their Windows Explorer. The good news is that Solaris 10 (9 as well) comes with SAMBA included in the OS, so you just need to enable it.

Configure Samba by creating the file /etc/sfw/smb.conf
Here's a minimal /etc/sfw/smb.conf which I used:

[global]
      workgroup = WORKGROUP
      server string = Fix Server
      log file = /var/samba/log/log.%M
      security = user

[logs]
      comment = FIX Log files
      path = /path/to/logs
      browseable = yes
      read only = yes
      guest ok = No
Add a user called "readlog" on Unix

# useradd -d /path/to/logs -s /bin/false readlog

Add the new created user "readlog" to the SAMBA password database and configure a password:

# /usr/sfw/bin/smbpasswd -a readlog
Now we can start Samba for the first time !

# /etc/init.d/samba start
Test the Samba Server by starting a new Windows Explorer and type \\yourserver in the address bar.
If everything is okay you'll get a password dialog where you can login with the username "readlog" and the password supplied at step 3.

Changing Veritas device owner for raw device

len — Thu, 18 Dec 2008 20:03:46 +0100

Today I had to set the owner/group for a Veritas raw device. You can set it on Unix using chown, but the settings will be lost after a reboot. To properly set the ownership on a veritas raw device you need the following command:

vxedit set user=username group=groupname mode=modenumber volumename

So in my case I did a

vxedit set user=informix group=informix mode=0660 rootdbs

Perl: how to install a Perl module locally

len — Tue, 16 Dec 2008 11:05:48 +0100

Today I wanted to install a Perl module in my home directory. Here's how to do it:

$ perl Makefile.PL PREFIX=/home/len
$ make
$ make test
$ make install

For older modules you might need to specify other variables during module installation.
I did it by saving the following variables in a file (install_vars.sh):

PREFIX=/home/len \
INSTALLPRIVLIB=/home/len/lib/perl5 \
INSTALLSCRIPT=/home/len/bin \
INSTALLSITELIB=/home/len/lib/perl5/site_perl \
INSTALLBIN=/home/len/bin \
INSTALLMAN1DIR=/home/len/lib/perl5/man \
INSTALLMAN3DIR=/home/len/lib/perl5/man/man3

Now you can use the following syntax:

$ perl Makefile.PL `cat install_vars.sh`
$ make
$ make test
$ make install

VMware Server: Managing virtual machines from the command line

len — Mon, 15 Dec 2008 16:54:01 +0100

Sometimes it's handy to be able to manage your Virtual Machines on the Command Line.
So if you are stuck in traffic and only have an SSH login available on your mobile phone,
here are the commands to manage your Virtual Machine:

Listing configured Virtual Machines:

$ vmware-cmd -l
/var/lib/vmware/Virtual Machines/Server-01/Windows 2000 Server.vmx
/var/lib/vmware/Virtual Machines/Server-01/RedHat5.vmx

Get the state of a Virtual Machine:

$ vmware-cmd "/var/lib/vmware/Virtual Machines/Server-01/RedHat5.vmx" getstate

Start (or resume) a Virtual Machine:

$ vmware-cmd "/var/lib/vmware/Virtual Machines/Server-01/RedHat5.vmx" start

Stop a Virtual Machine:

$ vmware-cmd "/var/lib/vmware/Virtual Machines/Server-01/RedHat5.vmx" stop

Reset a Virtual Machine:

$ vmware-cmd "/var/lib/vmware/Virtual Machines/Server-01/RedHat5.vmx" reset

Setting your X environment

len — Mon, 15 Dec 2008 14:15:01 +0100

Most Unix sysadmins are hardcore Command Line gurus. However, sometimes you may need to run a graphical application on Unix.
The graphical environment on Unix is called the X Window System (or X or X11). Unlike most other graphical systems, X is designed to be used over the network.

It's important to understand that in the X Window concept the application that runs on Unix is the Client, while your PC is the Server.
So the first thing you'll need is a X Server. On my Windows PC I have Reflection X installed (propertary software), but there are free alternatives, like Xming.

Once you have an X Server running on your PC, it's time to log in to the Unix box. On the Unix prompt you need to tell where the X Server resides. This is done by setting the DISPLAY variable:

$ DISPLAY=10.0.0.1:0 # Change 10.0.0.1 in your actual IP address
$ export DISPLAY

Now you can test the X Server by starting a X application, like xclock:

$ /usr/openwin/bin/xclock

A simple graphical clock should appear

Replacing text in multiple files

len — Mon, 15 Dec 2008 07:42:12 +0100

Here's a perl oneliner that does text search & replace over multiple files. Make sure you create a backup before using it !

This example will replace all occurences of "oldserver" to "newserver" in the *.conf files:

$ perl -pi -e 's/oldserver/newserver/g' *.conf

If you combine it with find you can even do search and replace recursively over directories.
This example will replace all occurences "10.0.0.1" to "192.168.1.1" in all files under /data:

$ find /data -type f | xargs perl -pi -e 's/10.0.0.1/192.168.1.1/g'

Linux: How to extract a single file from a RPM package

len — Fri, 12 Dec 2008 12:20:38 +0100

I once got myself in the situation where I had no option but to retrieve a missing file from a rpm package. I didn't want to install the whole rpm, but only extract the missing file. Here's an example how to extract the original httpd.conf from the httpd package:

Copy the rpm to your /tmp directory:

$ cp httpd-2.2.8-3.i386.rpm /tmp
$ cd /tmp
Get the absolute filename from the rpm:

$ rpm -qlp httpd-2.2.8-3.i386.rpm | grep httpd.conf
/etc/httpd/conf/httpd.conf
Extract the httpd.conf file from the rpm package:

$ rpm2cpio httpd-2.2.8-3.i386.rpm | cpio -id ./etc/httpd/conf/httpd.conf
4838 blocks
The requested file is now extracted in the /tmp directory:

$ ls -l /tmp/etc/httpd/conf/httpd.conf
-rw-r--r-- 1 root root 33692 2008-12-12 12:41 /tmp/etc/httpd/conf/httpd.conf

Solaris: Determinate to which package a file belongs

len — Fri, 12 Dec 2008 11:45:44 +0100

I had an issue with software which was complaining about the version of /usr/lib/libCstd.so.1
So I wanted to know to which package this particular file belongs, in order to see if there are any updates available for this package. Here's how to do it:

/usr/sbin/pkgchk -l -p <absolute filename or directory>

So in my case I ran:

$ /usr/sbin/pkgchk -l -p /usr/lib/libCstd.so.1
Pathname: /usr/lib/libCstd.so.1
Type: regular file
Expected mode: 0755
Expected owner: root
Expected group: bin
Expected file size (bytes): 1915796
Expected sum(1) of contents: 63488
Expected last modification: Oct 24 22:23:55 2008
Referenced by the following packages:
SUNWlibC
Current status: installed

As shown above the file /usr/lib/libCstd.so.1 belongs to package SUNWlibC.

The command pkgchk uses a flat file that contains the file and package information. You could as well directly use that:

$grep libCstd.so.1 /var/sadm/install/contents
/usr/lib/libCstd.so.1 f none 0755 root bin 1915796 63488 1224879835 SUNWlibC
/usr/lib/sparcv9/libCstd.so.1 f none 0755 root bin 2350704 39866 1224879861 SUNWlibCx