Archiv der Kategorie: CommandLine

more battery, please

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5

After I found out that the enhanced Gnome power manager applet has some trouble dealing with two batteries (it currently assumes you have only one and therefore it’s ability to guess the correct lifetime based on recent discharging times shows you definitely wrong spans when swapping the battery). But to be honest, this bug isn’t that grave to drop more words about this – I am quite sure it will be fixed soon.

More interesting instead is the possibility to save power. At least with gutsy you have the possibility to install Intel’s „powertop“ utility – a command line tool for measuring power consumption and detecting possible power leaks. I heard a lot of bad words about powertop, I for myself am quite satisfied about it and it’s documentation and hints on the website.

After dealing with it for some time, I wrote the following quite stupid but effective script, that extends my battery life time for some percent:

#!/bin/dash
# stop not essentially needed daemons
/etc/init.d/cupsys stop
/etc/init.d/tor stop
/etc/init.d/privoxy stop
/etc/init.d/bluetooth stop
/etc/init.d/racoon stop
/etc/init.d/postfix stop
/etc/init.d/cron stop
/etc/init.d/sysklogd stop
/etc/init.d/klogd stop
# decrease wlan power consumption (if wlan is not needed: switch it off!)
iwpriv eth1 set_power 5
# increase writeback time
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
# enable ac97 sound power save mode
echo 1 > /sys/module/snd_ac97_codec/parameters/power_save
# enable usb power save (actually not needed as it gets killed afterwards)
echo 1 > /sys/module/usbcore/parameters/autosuspend
# switch off usb
modprobe -r ehci_hcd
modprobe -r uhci_hcd
# switch off bluetooth
modprobe -r rfcomm
modprobe -r l2cap
modprobe -r bluetooth
# put harddisk to power save mode (spin down)
hdparm -B 1 -S 12 /dev/sda
# activate quiet hard disk mode - probably not needed when using the power save mode
hdparm -M 128 /dev/sda
# remount active partitions with noatime
mount -o remount,noatime /
mount -o remount,noatime /mnt/cryptdevice
# active laptop mode
echo 5 > /proc/sys/vm/laptop_mode

So you might guess I am not the hardware guru and you are right about it. But maybe this snippet is a good starting point for you to save some power. And yes, you can also save power on your desktop pc. It will not extend a battery lifetime but maybe the one of your purse.

Feel free to drop some of your hints or rants in the comment field.

Bashup – a sophisticated Bash backup script

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4

Mnemonikk (who still lacks a blog because he cannot decide which name to choose) finally made the step to create a sourceforge project for Bashup. Bashup is a more or less modular and Bourne shell compatible backup script with few dependencies. It targets backup for servers and provides features like mysql, oracle, postgresql, subversion repository and file system backup, backup over ftp, ssh, rsync, heavy rotation (yes – even over ftp) and reporting. The script is already used on a couple of different live servers. It matches the need for a script that is neither binary, nor python, ruby or perl but just plain shell and some external calls.

The script is released under GPL. Right now you can only get it by checking out the svn repository (see sourceforge project page for details) but will be branched with an official version number soon. I know there are a lot of backup solutions out there and this is just one more, but you might also know how difficult it can be to backup a system when having very limited possibilities to install software and servers distributed on very different data centers…

Feel free to contact me for gaining access as developer. Patches and new modules welcome!

/usr/bin/test not /usr/bin/[ anymore?

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5

I am really puzzled: While proudly presenting some linux knowledge I could not explain why /usr/bin/test and /usr/bin/[ are on Debian and Ubuntu (and maybe other distributions) not binary and symlink but different binaries. On Ubuntu Gutsy it looks like this:

[ccm:0:~]$ ls -l /usr/bin/test
-rwxr-xr-x 1 root root 23036 2007-09-29 14:51 /usr/bin/test
[ccm:0:~]$ ls -l /usr/bin/\[
-rwxr-xr-x 1 root root 25024 2007-09-29 14:51 /usr/bin/[
[ccm:0:~]$ md5sum /usr/bin/test
d83583f233cb4a014c2e9faef6bb9b32  /usr/bin/test
[ccm:0:~]$ md5sum /usr/bin/\[
b1e9282a48978a17fb7479faf7b8c8b7  /usr/bin/[

When playing around with them, they even behave different:

[ccm:0:~]$ /usr/bin/test --version
[ccm:0:~]$ /usr/bin/\[ --version
[ (GNU coreutils) 5.97

On Debian, Fedora, RedHat it looks the same. It puzzles me as just some weeks ago I read one of them is actually a symlink and think I the first test I made showed me machine where it behaved that way.

So maybe someone can update me why these binaries are different now. Guess there cannot be good reason as „man test“ and „man [“ show the same document:

ls -l /usr/share/man/man1/\[.1.gz
lrwxrwxrwx 1 root root 9 2007-12-04 19:20 /usr/share/man/man1/[.1.gz -> test.1.gz

And when answering this: „/usr/bin/test“ is part of coreutils, but /usr/bin/[ ?

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Using netcat and tar for network file transfer

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16

Imagine you are on lan party or on the road and quickly want to transfer a file or directory to another computer. Both computer owners are just to lazy to setup something like ftp, smb, nfs. A very simple and even cross platform solution is using netcat and in case of a directory in combination with tar like the following steps. I will just show you how to use it without compression for a directory. Fell free to play around. You can test it locally of course.

1. The sender

The sender has to call netcat in server mode and pipe content into it. The next line tells tar to build a tarball and write it to standard output which is redirected via a pipe to netcat. Netcat is told to start in server mode (-l), listen on port 7878 (-p 7878) and shutdown itself after waiting 10 seconds after having seen an end of file in standard input (-q 10):

$ tar c directory | nc -q 10 -l -p 7878

2. The receiver

The receiver has to call netcat and tell him to Weiterlesen →