Meeting: PLUG this Thurs, Jan 14th (With a change of a speaker)

[PLUG Announcements]

Due to unforeseen circumstances, we've had a last minute cancellation.

Joe Giron will not be able to make the meeting tomorrow so his 
presentation on MassScan will be postponed till next month.  Thankfully 
Aaron Jones has volunteered to step in in his place so we still have 2 
presentations for our meeting on Thursday.

Aaron Jones: CLI way to do things usually done with a GUI

Aaron is a web developer who enjoys using new technologies. He began 
using Linux while still a kid and is pro- VIM, GIT, CMUS, and 
NEWSBEUTER. His workflow is command line based and he hope's to help 
others learn more about computing, linux ,and the tools out there to 
make them more productive.

der hans: Anatomy of the Command Line

Order matters when the shell executes a command, but isn't strictly left 
to right. Redirects, functions, sub-shells, 
{brace,tilde,parameter,variable,arithmetic} expansion, pipes, globbing, 
regular expressions, command substitution and more.

What order does bash evaluate the different parts of the command line 
and what effect does that ordering have on the command? Which portions 
of the command are evaluated by the shell and which aren't?

The presentation will use command line examples to illustrate evaluation 
order for the various parts of a command.

For example:

grep foo file.txt >file.txt

That command results in file.txt being empty regardless of what the 
previous contents were ( provided file permissions allow the user to 
write to file.txt ). The reason is that the shell truncates file.txt 
before even starting up grep, so grep is actually searching a newly 
truncated empty file.

echo -n $( echo foo >>file.txt ) >file.txt

Again there is an empty file at the end even though foo is added to the 
file.txt during the command. In this case, the command subtitution and 
it's associated output redirection runs and completes before the outer 
shell and it's redirection. As a result, file.txt gets a line of input, 
then is truncated.
We go for food/Discussion afterward the meeting to BJs at the nearby mall.
---

The meeting will start at 7pm at The Desert Breeze Substation.  People 
start arriving as early as 6pm, so if you would like to help setup 
and/or chat for a while, arrive a little early.

Desert Breeze Substation
251 North Desert Breeze Blvd
Chandler, AZ 85226

The Desert Breeze Substation is on Chandler Blvd and Desert Breeze Blvd, 
which is half way between McClintock and Rural.  It is very close
to both the south 202 and 101 freeways.  Public transportation is
available into the late hours.

See http://phxlinux.org/meetings/14-east-valley-meeting.html for a map 
and other info.

See you there,
Brian Cluff

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