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Unix tools introduced. Today: cat

cat is a well known command to concatenate the content of multiple files.  Example: cat file1 file2 file3

But there are other use cases. cat offers a nice way to print out multi line strings.  It is even possible to include variables into the string, which feels a little bit like using a templating language.

Example:

NAME=ADMIN@COMPANY.COM;
cat <<EOF
Hello $LOGNAME,
please be aware. This system will be under maintenance soon.
Have a good day.
Sincerely
$NAME
EOF

For more info on the <<EOF visit this SO-Thread

 

 

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Public Money, Public Code

https://www.heise.de/newsticker/meldung/Erneuter-Kurswechsel-Muenchen-will-moeglichst-breit-auf-Open-Source-setzen-4716098.html

Open Source Produkte werden gerne überall genutzt. Öffentliche Institutionen könnten sich aber noch viel stärker an der Entwicklung von quelloffenen und frei verwendbaren Softwareprodukten beteiligen und damit zum allgemeinen Wohl beitragen.  Der rot-grüne Koalitionsvertrag von München weist interessante Punkte zu diesem Thema  auf.

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Leaving Amazon

https://www.tbray.org/ongoing/When/202x/2020/04/29/Leaving-Amazon

Amazon is exceptionally well-managed and has demonstrated great skill at spotting opportunities and building repeatable processes for exploiting them. It has a corresponding lack of vision about the human costs of the relentless growth and accumulation of wealth and power. If we don’t like certain things Amazon is doing, we need to put legal guardrails in place to stop those things. We don’t need to invent anything new; a combination of antitrust and living-wage and worker-empowerment legislation, rigorously enforced, offers a clear path forward.

Don’t say it can’t be done, because France is doing it.

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Gesundheitsakte per Injektion

MIT researchers have now developed a novel way to record a patient’s vaccination history: storing the data in a pattern of dye, invisible to the naked eye, that is delivered under the skin at the same time as the vaccine.

[…]

The researchers now plan to survey health care workers in developing nations in Africa to get input on the best way to implement this type of vaccination record keeping.

https://news.mit.edu/2019/storing-vaccine-history-skin-1218

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A tool to convert CSV, YML, XML, JSON and JSON-LD – oi v0.1

First release of oi is ready for testing. oi is an experimental command line tool to convert structured data from one format into another. The first release comes with rudimentary support for CSV, JSON, XML, YML and JSON-LD. The basic idea is to provide a straight in-out/out-in command that might not work completely correct but complements with other tools (jq, xsltproc,  sed, grep, awk, etc. ) to manipulate structured data on the command line.

Install

wget https://schnasse.org/deb/oi_0.0.1.deb
sudo apt install ./oi_0.0.1.deb # installs openjdk-11-jre

Example Usage

  1. Convert passwd to yml (use -t to print different formats)
oi /etc/passwd -d":" --header="login,password,uid,gid,comment,home,shell" -icsv
  1. List some disk info in yml (use -t to print different formats)
lsblk |grep -o sd.*|awk '{print $1 ";" $4 ";" $NF}'|oi -d";" --header="device,size,mount" -icsv
  1. Create adhoc Json-Ld Context for some arbitrary Json-API
curl https://api.github.com/users/jschnasse|oi -ijson -tcontext
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Command Line Tools: The growth of options

I found this table here: https://danluu.com/cli-complexity/

command 1979 1996 2015 2017
ls 11 42 58 58
rm 3 7 11 12
mkdir 0 4 6 7
mv 0 9 13 14
cp 0 18 30 32
cat 1 12 12 12
pwd 0 2 4 4
chmod 0 6 9 9
echo 1 4 5 5
man 5 16 39 40
which 0 1 1
sudo 0 23 25
tar 12 53 134 139
touch 1 9 11 11
clear 0 0 0
find 14 57 82 82
ln 0 11 15 16
ps 4 22 85 85
ping 12 12 29
kill 1 3 3 3
ifconfig 16 25 25
chown 0 6 15 15
grep 11 22 45 45
tail 1 7 12 13
df 0 10 17 18
top 6 12 14