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Posts from the ‘Command lines’ Category

10
May

Plymouth in 16.04 doesn’t automatically switch to login terminal

In Ubuntu 16.04, there is a bug in plymouth that it doesn’t automatically switch back when the boot process is finished. In fact, the splash screen is terminated and stayed in graphical terminal (VT7). Hence the user is stuck with a fsck screen output without login prompt that the user has to manually enter CTRL + ALT + Fn keys to login.

See this bug entry.

It takes me a while to come up with a workaround solution. Simply add the following line at the end of /etc/rc.local.

(sleep 1; chvt 1) &

However, I have no idea why simple ‘chvt 1’ won’t do the job but it works.

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1
Oct

Creating Bash 4.3.27 source package

Due to the severity of shellshock bug, I have to patch some of the internal legacy systems, like FreeBSD 8.0 which there are no more updates available. The only way I can update is to download the source from GNU site and build from that. However, the main source package is only available at version 4.3.0 at the time of writing. To remove the shellshock bug, it needs at least version 4.3.25. Although all the patches are located in the bash-4.3-patches directory, not of all them were created by pointing to “../bash-4.3” directory, some with different names.

So here it is, I have created this bash source package 4.3.27 with all these patches. I built it on FreeBSD and it passed the env test.

17
Nov

Extract a list of symbols from stock exchange indices

As far as I know there is no free web service that can produce a single page of stock symbols from a stock exchange. Moreover, for webpages that produce stock symbols, all of them only output with pagination. However, the easiest webpage to extract the symbols list is the Yahoo finance. This article shows how to extract a full list of symbols with a few repeated commands.

For Yahoo Finance, each page list approximately 50 symbols and it takes 3 calls to get all the symbols of FTSE 100 stock exchange. Here are the commands:

# Return the first 49 symbols
curl -s "http://uk.finance.yahoo.com/q/cp?s=%5EFTSE" | grep -o '>[A-Z]*\.L</a>' | sed -n "s/>\(.*\)<\/a>/\1/p"
# Return the next 50 symbols
curl -s "http://uk.finance.yahoo.com/q/cp?s=%5EFTSE&c=1" | grep -o '>[A-Z]*\.L</a>' | sed -n "s/>\(.*\)<\/a>/\1/p"
# Return the final symbol (last page)
curl -s "http://uk.finance.yahoo.com/q/cp?s=%5EFTSE&c=2" | grep -o '>[A-Z]*\.L</a>' | sed -n "s/>\(.*\)<\/a>/\1/p"

For Dow Jones Industrial Average, it returns 30 symbols

curl -s "http://finance.yahoo.com/q/cp?s=%5EDJI" | grep -o 'q?s=[A-Z]*">[A-Z]*' | sed -n 's/.*=.*">\([A-Z]*\)<\/a>/\1/p'

For Nasdaq Composite, it is the same as above except changing the cp query to s=%5IXIC and repeat for many pages with parameter c. Alternatively, you can use this link to download the whole list.

9
Sep

Emacs command line to indent Javascript code and convert tabs to spaces

Part of my project checkin script is to automatically apply coding style and converting tabs to spaces. Here is the command line:

emacs -batch file.js --eval "(custom-set-variables '(js-indent-level 2))"  -f mark-whole-buffer -f indent-region -f mark-whole-buffer -f untabify -f save-buffer -kill

Change the value of js-indent-level to any religion of white spaces.

29
Jul

How to extract storage device information (Parte 2 – using lshw and xmlstarlet)

In Ubuntu 10.04, udevinfo is no longer available and I need to write a LiveCD tool to retrieve storage information (such as vendor, size, filesystem, label) from existing partitions (e.g /dev/sda1). So I cannot use the command lines anymore mentioned in my previous blog.

After a day of researching various tools and experiment parsing command line outputs. Eventually, I decide to use lshw to generate all the storage information and output into XML format. Then use xmlstarlet to extract specific device data. Read more »