Meld as SVN diff

The default Subversion's diff program can be replaced by, e.g., meld. In fact, it may also be used as merge program, but we do not address to this issue here.

To use melt as diff program, open with a text editor the file

~/.subversion/config

and replace or add the line

diff-cmd=meld

Then the command

svn diff -r v1:v2 FILE &

will compare the versions v1 and v2 of FILE using meld.

Mathematica and SSH

DISCLAIMER: we strongly discourage usage of proprietary software, since it violates fundamental user freedoms.
 
To run Mathematica on a remote machine, e.g., via ssh

$ ssh -X user@machine.domain.com

it is useful to not execute commands using the GUI. In fact, if the network is not optimal (like Internet), the computation would be drastically slowed down. Instead, one should run a Mathematica package via command line.

The steps to evaluate a sequence of Mathematica cells using a script are as follows:

1. write the program using the Mathematica notebook as usual;
2. select a cell, copy the content as InputForm, and paste it into a text file;
3. repeat the step above for all the cells;
4. save the text file with .m extension.

Then the package can be evaluated as:

$ math -script file.m

Alternatively, one may add a line at the beginning of the script, which will look as follows:

#!/usr/local/bin/MathematicaScript -script

(* output a file containing Cos[x] *)
Export["output.dat",Table[{x,N[Cos[x]]},{x,0,Pi}]]

Then make executable the script:

$ chmod a+x script.m

and run it:

$ ./script.m

To keep the run also without keeping the shell open, use:

$ nohup ./script.m &


Refs: Mathematica Docs, Bergman Lab

CPU fan on Lenovo Thinkpad T420

Content:

• Debian 8
• Configuration
• Enable the service
• Avoid overheating
• Ubuntu 11.10

Debian 8

While the fan behaves reasonably under Debian 8, I wanted to increase its usage as I often run short but CPU consuming processes. Thinkfan, originally created to solve the problem of unnecessary  high fan consumption (see the section below about Ubuntu). It provides an easy way in general to control the fan level for given temperature ranges.

Configuration

Install the packages

# apt-get install thinkfan lm-sensors

I encountered an error during installation, which is a known bug. This happens because it tries to load the service before it is properly configured. This error does not prevent the following steps for a proper configuration.

Setting up thinkfan (0.9.2-1) ... Job for thinkfan.service failed. See 'systemctl status thinkfan.service' and 'journalctl -xn' for details. invoke-rc.d: initscript thinkfan, action "start" failed. dpkg: error processing package thinkfan (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: thinkfan E: Sub-process /usr/bin/dpkg returned an error code (1)

Scan the system (answer all the default options)

# sensors-detect

Search for thermal sensors

$ find /sys/devices -type f -name "temp*_input"

My output looks like:

/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/hwmon/hwmon3/temp1_input
/sys/devices/virtual/hwmon/hwmon0/temp1_input
/sys/devices/platform/coretemp.0/hwmon/hwmon2/temp3_input
/sys/devices/platform/coretemp.0/hwmon/hwmon2/temp1_input
/sys/devices/platform/coretemp.0/hwmon/hwmon2/temp2_input

Add the devices to the file

/etc/thinkfan.conf 

appending 'hwmon' to each line (in my case I excluded the first line of the previous output), so that the file would look something like this:

hwmon /sys/devices/virtual/hwmon/hwmon0/temp1_input
hwmon /sys/devices/platform/coretemp.0/hwmon/hwmon2/temp3_input
hwmon /sys/devices/platform/coretemp.0/hwmon/hwmon2/temp1_input
hwmon /sys/devices/platform/coretemp.0/hwmon/hwmon2/temp2_input

(0,    0,    55)
(1,    48,    60)
(2,    50,    61)
(3,    52,    63)
(4,    56,    65)
(5,    59,    66)
(7,    63,    32767)

The numbers correspond to:

(LEVEL, LOW, HIGH)
LEVEL is the fan level to use (0-7 with thinkpad_acpi)
LOW is the temperature at which to step down to the previous level
HIGH is the temperature at which to step up to the next level
All numbers are integers.

For more informations see the comments in the template configuration file

/usr/share/doc/thinkfan/examples/thinkfan.conf.simple

Enable the service

Enable the kernel module:

# modprobe thinkpad_acpi fan_control=1

Now that the module parameter fan_control=1 has been given to thinkpad-acpi, the fan levels can be set manually, e.g.:

echo level 4 | sudo tee /proc/acpi/ibm/fan

where the level can be set to an integer between 0 (no fan) 7 (high fan level). Note that level 7 (about 4500 rpm) does not correspond to the maximum speed reachable by the fan. It is possible to increase further the fan usage manually by setting the level to 'disengaged' (about 5500rpm)

echo level disengaged | sudo tee /proc/acpi/ibm/fan

and return back to automatic mode as

echo level auto | sudo tee /proc/acpi/ibm/fan

It is however preferable and more safe to start an automatic service, such as thinkfan, to control the fan level given certain temperature ranges.

Start the thinkfan service:

# systemctl start thinkfan.service

In no error appears, the service should be enabled. The following should inform you that thinkfan is active

$ systemctl status thinkfan.service

You can also check the fan level

$ cat /proc/acpi/ibm/fan
status:        enabled
speed:        1985
level:        1
commands:    level ( is 0-7, auto, disengaged, full-speed)
commands:    enable, disable
commands:    watchdog ( is 0 (off), 1-120 (seconds))
where ' level' is set between 0-7. If instead of being set to a number it is set to 'auto', then probably thinkfan is not active.

or using the command

$ sensors

Finally, load the module at boot:

# echo "options thinkpad_acpi fan_control=1" | sudo tee /etc/modprobe.d/thinkpad_acpi.conf

and enable the service at boot

# systemctl enable thinkfan.service

Avoid overheating

The temperature can still rise significantly (> 90C) when intense CPU usage is required. First, you may want to clean the heat sink. If it does not help, or if to clean the fan you wish anyway to disassemble the machine, it is probably required also the replacement of the thermal paste. Check your hardware maintenance manual to see how to disassemble the heatsink. Other unofficial sources (e.g. videos) may also be useful, but the official manual should be consulted, since this is a potentially dangerous procedure (even if easy).

Apart from mechanical solutions, it is also possible to force a reduced CPU usage. E.g., it may be required that CPUs are loaded only up to 80% of their capacities:

# echo 80 > /sys/devices/system/cpu/intel_pstate/max_perf_pct

A systemd script to set automatically the CPU levels at boot can be downloaded from here. Of course, this is not the optimal long term fix, but it is not invasive and requires no purchase.

Ubuntu 11.10

DISCLAIMER: while we keep this section for reference, we strongly discourage usage of Ubuntu, in particular those versions released between year 2012 and 2016 implementing spyware.

After installing Ubuntu 11.10 on a Lenovo Thinkpad T420, the fan always run too much, even if there is a minimal CPU usage. The solution is installing the package thinkfan, and care attention to wisely configure the fan options.

These steps solve the problem:

1. Install thinkfan package:

$ sudo apt-get install thinkfan

2. Add kernel module ‘coretemp’ to /etc/modules

$ sudo sh -c ‘echo coretemp >> /etc/modules’

3. Load kernel module ‘coretemp’

$ sudo modprobe coretemp

4. Add the following three sensor entries to /etc/thinkfan.conf just before the temperature levels:

sensor /sys/devices/platform/coretemp.0/temp1_input
sensor /sys/devices/platform/coretemp.0/temp2_input
sensor /sys/devices/platform/coretemp.0/temp3_input
sensor /sys/devices/virtual/hwmon/hwmon0/temp1_input

5. Add the following to /etc/modprobe.d/thinkfan.conf: ‘options thinkpad_acpi fan_control=1′

$ sudo sh -c ‘echo “options thinkpad_acpi fan_control=1″ >> /etc/modprobe.d/thinkfan.conf’

6. Reload kernel module ‘thinkpad_acpi’

$ sudo modprobe -r thinkpad_acpi
$ sudo modprobe thinkpad_acpi

7. Set START=”yes” in /etc/default/thinkfan

8. Start thinkfan:

$ sudo /etc/init.d/thinkfan start

9. Check whether it works

$ sudo cat /proc/acpi/ibm/fan

if level has a value between 0 and 7, and changes by times, your thinkfan daemon works.

10. Add thinkfan to startup applications.

Ref: Putokaz, Debian forum and mailing list, thinkwiki, stackexchange

Gnuplot

Basic code to print plots, also using symbols like greek letters:

set term post color eps enh
set output "plot.eps"
set title "{/Symbol abcdefghijklmnopqrstuvwxyz \245}"


See also this page and, in particular, this script.