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Posts about tips (old posts, page 1)

Using the clipboard with Vim

Via Planet Debian: Enrico Zini posts about using the clipboard with vim

Two cool things I learned from Enrico's post:

  1. xclip is cool. Especially with combined with zsh. Say you want to have the output of a command printed to the terminal, but also copied to the clipboard. sha1sum * | tee >(xclip)
  2. I read the x11-selection help page in vim and discovered that you can access the copy/paste clipboard with the '+' register. Wow! No more pasting in text, having the indentation screwed up, undoing, setting paste mode, pasting again, unsetting paste mode!

Kill zem all!

Wow!

Every good linux user knows about the kill command. You use it all the time to kill off out of control or dead processes.

kill 1234
will kill off the process with pid 1234.

But did you know that

kill -TERM -1234
will kill off all processes in 1234's process group? I didn't until just a few minutes ago! Super-handy!

Disowning your children (in bash/zsh)

You learn something new every day!

Today I learned about the disown builtin in bash and zsh. When you disown a job, it will no longer receive a HUP signal when you exit your shell.

[email protected]:~ [1015]% while true; do date >> date.log; sleep 10; done&

[1] 7380

So now you've got the current date being appended to date.log every 10 seconds.

Try exiting your shell:

[email protected]:~ [1016%1]% exit

zsh: you have running jobs.

But use the disown command:

[email protected]:~ [1017%1]% disown %1

[email protected]:~ [1018]% exit

and your shell exits without complaining. Meanwhile, your job keeps running in the background!

Ahhhhhh...Breathing room!

At least that's the way it feels!

I just realized that my laptop supports 1600x1200 resolution! And I've been running it at 1024x768 all this time!

So after fighting with the fglrx drivers for Debian, I can finally surf the web and read e-mails without having to scroll left and right all the time!

Setting up fglrx was less than painless to put it mildly. For future reference, I had to do something like this:

aptitude install fglrx-kernel-src

cd /usr/src

tar jxf fglrx.tar.bz2

cd modules/fglrx

export KVERS=2.6.16-1-686

export KSRC=/usr/src/linux-headers-${KVERS}

debian/rules binary_modules

I would have hoped that m-a a-i fglrx would have worked, but alas...

Oh, and other thing. ATI: it isn't cool to lock up the machine just because your driver doesn't support 16 bit colour. I had set my default colour depth to 16bpp previously in an effort to get higher resolution with the radeon driver, but when I started using the fglrx driver things would just lock up.

svn-commit

Hate it when you write a big long commit message in subversion, and then the commit fails for some reason and you have to commit again?

Tired of reading in the aborted commit log message into new commit log?

Can't remember what subversion calls the aborted log messages?

Me too.

So I wrote this little plugin for vim that will look in the current directory for any aborted subversion commit logs. It will pick the newest one, and read that in. Just put this script into ~/.vim/ftplugin and name it something starting with "svn" and you should be good to go!

" SVN aborted commit log reader

" Reads in the newest svn-commit.tmp log in the current directory

" (these get left behind by aborted commits)

"

" Written by Chris AtLee

" Released under the GPLv2

" Version 0.2

function s:ReadPrevCommitLog() " Get the newest file (ignoring this one) let commitfile = system("ls -t svn-commit.tmp | grep -v " . bufname("%") . " | head -1") " Strip off trailing newline let commitfile = substitute(commitfile, "\s\n$", "", "") " If we're left with a file that actually exists, then we can read it in if filereadable(commitfile) " Read in the old commit message "echo "Reading " . commitfile silent exe "0read " . commitfile

    " Delete everything from the first "^--This line" to the last one
    normal 1G
    let first = search("^--This line", "")
    normal G$
    let last = search("^--This line", "b") - 1

    if last > first
        silent exe first . "," . last . "d"
    endif
    normal 1G
    set modified
endif

endf

call s:ReadPrevCommitLog()

Munin plugin for Shorewall accounting

I wrote this little script to monitor traffic on various machines at work. We use Shorewall to set up all the netfilter rules, traffic shaping, etc. It also makes it easy to set up rules to monitor traffic for different types of traffic.

We use Munin to track all sorts of things over time. The script below is a Munin plugin that will create a graph with one data series for each of the chains defined in your shorewall accounting file.

Put this script into /etc/munin/plugins and call it something like shorewall_accounting, and then add this in /etc/munin/plugin-conf.d/munin-node:

[shorewall_accounting]

user root

The name in between the square brackets should match the name of the file you saved the script in. The script needs to run as root in order to get access to iptables.

Edit Jan 20, 2006: Some minor bugfixes to the script have now been included. The shorewall accounting chains are now output in alphabetical order, and the regexp has been fixed to catch very large numbers.

#!/usr/bin/python

# shorewall_accounting

# A munin plugin for tracking traffic as recorded by shorewall accounting rules

# Written by Chris AtLee 

# Released under the GPL v2

import sys, commands, re

accountingLineExp = re.compile(r"^\s*\d+\s+(\d+)\s+(\w+).*$")



def getBytesByChain():
    status, output = commands.getstatusoutput("shorewall -x show accounting")
    if status != 0:
        raise OSError("Error running command (%s)[%i]: %s" % (trafficCmd, status, output))
    chains = {}
    for line in output.split("\n"):
        m = accountingLineExp.match(line)
        if m is not None:
            target = m.group(2)
            bytes = int(m.group(1))
            if target in chains:
                chains[target] += bytes
            else:
                chains[target] = bytes
    retval = []
    chainNames = chains.keys()
    chainNames.sort()
    for name in chainNames:
        retval.append((name, chains[name]))
    return retval


if len(sys.argv) > 1:
    if sys.argv[1] == "autoconf":
        print "yes"
        sys.exit(0)
    elif sys.argv[1] == "config":
        print "graph_title Shorewall accounting"
        print "graph_category network"
        print "graph_vlabel bits per ${graph_period}"
        for chain,bytes in getBytesByChain():
            print "%s.min 0" % chain
            print "%s.type DERIVE" % chain
            print "%s.label %s" % (chain, chain)
            print "%s.cdef %s,8,*" % (chain, chain)
        sys.exit(0)


for chain, bytes in getBytesByChain():
    print "%s.value %i" % (chain, bytes)

Getting Thunderbird to open links in Firefox (not Mozilla!)

I got sick of Thunderbird opening up links in Mozilla instead of Firefox. A friend mentioned that the preference responsible for opening up links was 'network.protocol-handler.app.http'. I searched around in the Thunderbird pref files for what it was currently using. On my machine it was set to launch 'x-www-browser'. This is actually a symlink into Debian's alternatives directory, so a simple

update-alternatives --set x-www-browser /usr/bin/firefox

did the trick.