The Program "screen" Rocks!

# use screen in a script to detach a given program
screen -d -m <program_to_detach>

# list existing screen sessions
screen -ls

# attach to a previously screened program
screen -r <screen_id>

# detach from the currently attached screen session
CTRL-A, CTRL-D

Ubuntu 7.10, Cisco VPN Related Packages

These are the Cisco VPN related packages that I believe are needed for my Ubuntu 7.10 Desktop:

network-manager, network-manager-gnome, network-manager-vpnc, vpnc

As a side note, I ended up not using vpnc. I ended up using the Cisco 4.8.00.0490-k9 client code and patching it. Basically, I ended up following the instructions as documented by "peteguhl" here:

Howto: Cisco VPN client on x86_64

I am almost tempted to paste a complete copy of those instructions here, but I'll hold off on that for now.

The control script is here: /etc/init.d/vpnclient_init

To connect, issue: "vpnclient connect <profile_name>"

Some Handy Git Commands

# Grab some GIT stuff
git clone <git_reference>

# Possible GIT workflow. One person team. Master branch.
git pull <git_reference>
git add <filesystem object>
git commit -m 'Comment here' <filesystem object>
git push <git_reference>

# See what is different
git diff

Some Handy CVS Commands

# Checkout a Module
cvs co <module>

# Checkout a Module from a given branch, MY_BRANCH_TAG
cvs co -rMY_BRANCH_TAG <module>

# Display log associated with a file
cvs log <file>

# Update the Module with any new code committed
cvs update <module>

# Add a new binary file
cvs add -kb <binary_file>
cvs commit

# Review list of files that have been modified in your diretory
cvs -qn up

Mini Fake Python DNS Server

Google: "pyminifakeDNS"
Code here

A Windows TFTP / DHCP Server

TFTPD32 (Philippe Jounin (philippe@jounin.net))

Some Excellent Dot Net Tools

.NET Reflector (Lutz Roeder)
SharpDevelop (IDE)

Handy Find Command

Find all files on a given filesystem, capturing some nice attributes about them:

find / -xdev | xargs stat -c "%n %a %u %g" | sort > file.txt

VIM: Finding Lines With Bytes In CC 81 Or More

To find and highlight all lines containing characters in card column (CC) 81 and greater, use the following search:

/^.\{81,}

Some Networking Benchmark Tools

-- iperf
-- NetPIPE
-- ttcp

Loopback Mount of ISO Example

mount -o loop -t iso9660 isoimagefile.iso /mnt/iso9660image

Converting Unix Man Pages To Text

Generally, this kind of thing will work:

zcat /usr/share/man/man1/chmod.1.gz | nroff -man | col -bx > chmod-1-man.txt
zcat /usr/share/man/man8/e2fsck.8.gz | nroff -man | col -bx > e2fsck-8-man.txt
zcat /usr/share/man/man8/fdisk.8.gz | nroff -man | col -bx > fdisk-8-man.txt

Handy "rdesktop" Command From Linux

rdesktop -u <windows_user_name> -g 90% <ip_address>

SSH Tunneling Example (X Forwarding)

Machine A is a machine with an active X-Window server and the necessary SSH client software. Machine B is a Linux machine with SSHD running that we have root access to. Machine C is also a Linux machine that we have an account on. From A, we are going to create an SSH tunnel through B which accesses C and displays X-Window client applications back on A via the tunnel. Do something like this:

ssh -X -l root -L 22:<C_IP_ADDRESS>:22 -N <B_IP_ADDRESS>

-- Supply the root password for B when prompted.
-- Supply the correct login/password for C when prompted.
-- Port 22 is the default port for SSH.
-- Execute an X-Window client application on C to test. Maybe "xeyes" or "xclock".
-- If there are problems, open up the privileges for the X-Window server on A with an "xhost +"

SSH Tunneling Example (RDP)

Machine A is an XP machine with Cygwin installed, including the necessary SSH client related software. Machine A also has the remote desktop protocol (RDP) client software installed. Machine B is a Linux machine with SSHD running that we have have root access to. Machine C is an XP machine that allows incoming RDP sessions provided the client has the correct credentials. To use A to take over C via an SSH tunnel through B, do something like this from a Cygwin shell on A:

ssh -l root -L 55555:<C_IP_ADDRESS>:3389 -N <B_IP_ADDRESS>

-- Supply the root password for B when prompted.
-- Then, use the RDP client on A to connect to C via localhost:55555.
-- Supply the correct login data items for C.
-- Port 3389 is the default RDP port.
-- On an XP machine, the RDP client software is "mstsc.exe"

Some ClearCase Operations

Assumptions:

-- "cleartool" is in $PATH and aliased to "ct"
-- /admin-vob is the Unix path for special admin version object base (VOB)
-- "main_view" is a default view with the following config spec:

element * CHECKEDOUT
element * /main/LATEST

Operations:

# Creating a branch type that is available to all VOBS
# associated with the admin VOB

$ ct setview main_view
$ cd /admin-vob
$ ct mkbrtype -global -c "<comment>" <branch_name>

# Creating a label type that is available to all VOBS
# associated with the admin VOB

$ ct setview main_view
$ cd /admin-vob
$ ct mklbtype -global -c "<comment>" <label_name>

# Applying a label types to stuff recursively (already in a view):

$ ct mklabel -recurse -c "<comment>" <label_name> <start path>

# Applying a label type to an individual element (directory):

$ ct mklabel -c "A Directory" MY_LABEL /vob-at-hand/a/b/c/d

# Applying a label type to an individual element (file):

$ ct mklabel -c "A File" MY_LABEL /vob-at-hand/a/b/c/d/random.xml

# Locking a branch type that is available to all VOBS
# associated with the admin VOB

$ ct setview main_view
$ cd /admin-vob
$ ct lock -replace brtype:<branch_name_to_lock>

# Locking a label type that is available to all VOBS
# associated with the admin VOB

$ ct setview main_view
$ cd /admin-vob
$ ct lock -replace lbtype:<LABEL_TO_LOCK>
# Rename a branch type that is available to all VOBS
# associated with the admin VOB

$ ct setview main_view
$ cd /admin-vob
$ ct rename brtype:<src_branch_name> brtype:<tgt_branch_name>

# NOTE: Of course, any views that were looking for the old
branch tag need to have their config specs fixed.

# Rename a label type that is available to all VOBS
# associated with the admin VOB

$ ct setview main_view
$ cd /admin-vob
$ ct rename lbtype:<SRC_LABEL> lbtype:<TGT_LABEL>

# Create a ClearCase dynamic view in view storage.

$ cd /view-storage
$ umask 002
$ ct mkview -tag <view_name> <view_name>.vws

# Removing a ClearCase dynamic view:

$ cd /view-storage
$ ct rmview -force <view_tag.vws>

# NOTE: should ensure that there are no checkouts in view
# before removal.

# Listing the visible elements (sorted) from within a view:
$ ct ls -r -s -visible . | sort

Solaris Package Manager Tips

On a Solaris machine, which packages are present?

/usr/bin/pkginfo -x

Given a package name, which files are related?

/usr/sbin/pkgchk -l <package name>

Given a package name, display package information:

/usr/bin/pkginfo -l <package name>

Given a file name, display related package information:

/usr/sbin/pkgchk -l -p /usr/bin/ls

RPM Tips

Given a file, which package is it in?

# rpm -q -f <file>

Given a package name, which files are related?

# rpm -ql <package>

Given a package name, display package information:

# rpm -qi <package>

Dump all package names:

# rpm -qa | sort | more

Dump all package information:

# rpm -qai

Search uninstalled RPMs for a file:

# ls -1 *.rpm | xargs rpm --query --filesbypkg --package | grep <search_pattern>

Note: The tip above was adapted from the Nov 2008 Linux Journal "Tech Tip" by Dashamir Hoxha on page 31.

Using Old Micron PCs For Rsync (via SSH) Targets

At a high level, here is what I did to configure three(3) old Micron boxen (Pentium 3, 500MHz, 64MB RAM, 13.5GB) to serve exclusively as rsync targets for production data:

1) Burnt a debian (etch) 4.0r2-i386 "netinst" CD.
2) Booted CD with "netcfg/disable_dhcp=true" option so that I could conduct static network configuration during the install.
3) Used following partition sizes: 800MB (/), 256MB (swap), and 12.6GB (/data).
4) Installed the minimal set of software I could get away with using the non-expert path.
5) Took CD out, rebooted.
6) apt-get install openssh-server (I used the "netinst" CD to satisfy this)
7) apt-get install rsync
8) Rebooted.

Note: I had to setup the BIOS to not halt on detecting a missing keyboard since the intention is to use them like that (no head either).

Rsync Example

Using rsync to execute an initial copy of data from the SOURCE to TARGET machine via a SSH transport:

rsync -avx --numeric-ids --progress -e ssh /data/ root@<TARGET_IP_ADDRESS>:/data

Using rsync to maintain synchronization after the initial copy:

rsync -avx --numeric-ids --progress --delete -e ssh /data/ root@<TARGET_IP_ADDRESS>:/data

-- The "--delete" option has been added to delete files from the TARGET that have been deleted from the SOURCE since the initial rsync.

-- The "--dry-run" or "-n" option can be added to reveal what rsync intends to do.

-- The trailing "/" on the SOURCE directory is intentionally there and keeps that directory from being created under the TARGET subdirectory.