Meeting-20100612 - Revision history

Vance: /* EXERCISE TWO */ formatting

2010-06-13T07:48:48Z

EXERCISE TWO: formatting

← Older revision		Revision as of 07:48, 13 June 2010
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	Let's pick apart the regex to see what it does.		Let's pick apart the regex to see what it does.

			<font color="red">'''^'''</font>[-+]?([0-9]+\.?\|[0-9]*\.[0-9]+)$
	;^		;^
	:The ^ at the beginning means that our regex will only match starting at the beginning of the line. The anticipated use for this command is something like 'echo "$value" \| grep blah...', so we know there won't be any extraneous stuff at the beginning. If you are getting the value from a file or as input from the user, you may need to strip away whitespace from the beginning, or alter the regex to account for that.		:The ^ at the beginning means that our regex will only match starting at the beginning of the line. The anticipated use for this command is something like 'echo "$value" \| grep blah...', so we know there won't be any extraneous stuff at the beginning. If you are getting the value from a file or as input from the user, you may need to strip away whitespace from the beginning, or alter the regex to account for that.

			^<font color="red">'''[-+]'''</font>?([0-9]+\.?\|[0-9]*\.[0-9]+)$
	;[-+]		;[-+]
	:An expression inside brackets matches a single character, as long as that character is one of those listed inside the brackets (a range of characters can be specified, as can special pre-defined character classes, but in this case we're not using either of those). So this would match either a - sign or a + sign. Note that inside a bracket expression, + has no special meaning.		:An expression inside brackets matches a single character, as long as that character is one of those listed inside the brackets (a range of characters can be specified, as can special pre-defined character classes, but in this case we're not using either of those). So this would match either a - sign or a + sign. Note that inside a bracket expression, + has no special meaning.

			^<font color="red">'''[-+]?'''</font>([0-9]+\.?\|[0-9]*\.[0-9]+)$
	;[-+]?		;[-+]?
	:The question mark means "match zero or one of the preceding character." This makes it so that having a sign at the beginning of our number is optional, and also disallows multiple sign characters.		:The question mark means "match zero or one of the preceding character." This makes it so that having a sign at the beginning of our number is optional, and also disallows multiple sign characters.

			^[-+]?<font color="red">'''([0-9]+\.?\|[0-9]*\.[0-9]+)'''</font>$
	;( ... \| ... )		;( ... \| ... )
	:The parentheses are there for grouping what's inside as a single unit. The pipe symbolizes alternation - that is, this part of the regex will match either the expression appearing before the pipe symbol, or the expression appearing after it. We need to use alternation because while it is optional to have numbers before the decimal point (e.g., .123) or after the decimal point (e.g., 123.), it is not valid for both sets of numbers to be missing (e.g., just a .).		:The parentheses are there for grouping what's inside as a single unit. The pipe symbolizes alternation - that is, this part of the regex will match either the expression appearing before the pipe symbol, or the expression appearing after it. We need to use alternation because while it is optional to have numbers before the decimal point (e.g., .123) or after the decimal point (e.g., 123.), it is not valid for both sets of numbers to be missing (e.g., just a .).

			^[-+]?(<font color="red">'''[0-9]'''</font>+\.?\|[0-9]*\.[0-9]+)$
	;[0-9]		;[0-9]
	:Another bracket expression, this matches any single numeral (that is, any character in the range 0 through 9).		:Another bracket expression, this matches any single numeral (that is, any character in the range 0 through 9).

			^[-+]?(<font color="red">'''[0-9]+'''</font>\.?\|[0-9]*\.[0-9]+)$
	;[0-9]+		;[0-9]+
	:The + sign outside a bracket expression does have special meaning. It means "match one or more of the preceding character." So this will match one or more numerals, but not an empty string.		:The + sign outside a bracket expression does have special meaning. It means "match one or more of the preceding character." So this will match one or more numerals, but not an empty string.

			^[-+]?([0-9]+<font color="red">'''\.'''</font>?\|[0-9]*\.[0-9]+)$
	;\.		;\.
	:The dot has the special meaning "match any character." If we want to literally match a period, we have to escape it with a backslash to remove its special meaning. Note that '''[.]''' would do the same thing, as dot has no special meaning inside a bracket expression.		:The dot has the special meaning "match any character." If we want to literally match a period, we have to escape it with a backslash to remove its special meaning. Note that '''[.]''' would do the same thing, as dot has no special meaning inside a bracket expression.

			^[-+]?([0-9]+<font color="red">'''\.?'''</font>\|[0-9]*\.[0-9]+)$
	;\.?		;\.?
	:Again, question mark means to match zero or one of the preceding character. This makes the decimal point optional.		:Again, question mark means to match zero or one of the preceding character. This makes the decimal point optional.

			^[-+]?(<font color="red">'''[0-9]+\.?'''</font>\|[0-9]*\.[0-9]+)$
	;[0-9]+\.?		;[0-9]+\.?
	:This is the entire first expression of our alternation. It will match an integer of any length, optionally followed by a decimal point. So 0, 123, 123., 00000., 000123, and 123123123123123123123 would all match, but just a decimal point would not.		:This is the entire first expression of our alternation. It will match an integer of any length, optionally followed by a decimal point. So 0, 123, 123., 00000., 000123, and 123123123123123123123 would all match, but just a decimal point would not.

			^[-+]?([0-9]+\.?\|<font color="red">'''[0-9]*'''</font>\.[0-9]+)$
	;[0-9]*		;[0-9]*
	:We've seen [0-9] before, but the * is new. It is similar to +, but means "match zero or more of the preceding character." We use * instead of + because it's valid to have nothing in front of the decimal point (e.g., .123).		:We've seen [0-9] before, but the * is new. It is similar to +, but means "match zero or more of the preceding character." We use * instead of + because it's valid to have nothing in front of the decimal point (e.g., .123).

			^[-+]?([0-9]+\.?\|[0-9]*<font color="red">'''\.'''</font>[0-9]+)$
	;\.		;\.
	:This matches a decimal point again, but note there is no question mark. In this expression, one single decimal point is mandatory.		:This matches a decimal point again, but note there is no question mark. In this expression, one single decimal point is mandatory.

			^[-+]?([0-9]+\.?\|[0-9]*\.<font color="red">'''[0-9]+'''</font>)$
	;[0-9]+		;[0-9]+
	:Again, this matches one or more numerals. Having numbers after the decimal point is not optional here.		:Again, this matches one or more numerals. Having numbers after the decimal point is not optional here.

			^[-+]?([0-9]+\.?\|<font color="red">'''[0-9]*\.[0-9]+'''</font>)$
	;[0-9]*\.[0-9]+		;[0-9]*\.[0-9]+
	:This is the full second expression of our alternation. It will match any floating point value, such as 0.123, 1.234, .123, 0098.6, 123.456, or 3.1415926535897932384626433832795028841971693993751.		:This is the full second expression of our alternation. It will match any floating point value, such as 0.123, 1.234, .123, 0098.6, 123.456, or 3.1415926535897932384626433832795028841971693993751.

			^[-+]?<font color="red">'''([0-9]+\.?\|[0-9]*\.[0-9]+)'''</font>$
	;([0-9]+\.?\|[0-9]*\.[0-9]+)		;([0-9]+\.?\|[0-9]*\.[0-9]+)
	:This is the full non-sign part of our regex. As discussed above regarding alternation, it means "either an integer, optionally followed by a decimal point, or an optional set of numerals followed by a (mandatory) decimal point and one or more trailing numerals."		:This is the full non-sign part of our regex. As discussed above regarding alternation, it means "either an integer, optionally followed by a decimal point, or an optional set of numerals followed by a (mandatory) decimal point and one or more trailing numerals."

			^[-+]?([0-9]+\.?\|[0-9]*\.[0-9]+)<font color="red">'''$'''</font>
	;$		;$
	:This is the counterpart to the ^ character, forcing a match at the end of the line. Putting the expression inside ^$ forbids any extraneous characters before or after our match.		:This is the counterpart to the ^ character, forcing a match at the end of the line. Putting the expression inside ^$ forbids any extraneous characters before or after our match.

Vance: /* EXERCISE ONE */

2010-06-13T04:46:34Z

EXERCISE ONE

← Older revision		Revision as of 04:46, 13 June 2010
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	sys 0.12		sys 0.12

	~~time -p~~ grep -c . filename		grep -c . filename
	3000000		3000000
	real 0.94		real 0.94

Vance: /* Meeting Minutes */

2010-06-13T04:34:17Z

Meeting Minutes

← Older revision		Revision as of 04:34, 13 June 2010
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	== Meeting Minutes ==		== Meeting Minutes ==

	~~(TBA)~~		'''DRAFT'''

			The regular monthly meeting of the Western Pennsylvania Linux Users Group was held on Saturday, June 12, 2009, at 11:06 AM, at the Wilkins School Community Center, the regular presiding officer being in the chair. In the absence of the regular secretary, Vance Kochenderfer was elected to serve as secretary pro tem. The [[Meeting-20091031#Meeting_Minutes\|minutes of the October 31, 2009 meeting]] were approved as read.

			The Treasurer reported that there is $760.80 in the checking account, $66 cash on hand in the refreshment fund, and $40 received in dues yet to be deposited.

			The meeting adjourned at 11:09 AM.

			Vance Kochenderfer<br />
			Secretary pro tem

			'''DRAFT'''

	== Meeting Staff ==		== Meeting Staff ==

Vance: /* EXERCISE TWO */

2010-06-13T04:11:14Z

EXERCISE TWO

Show changes

Vance: /* EXERCISE ONE */

2010-06-13T03:53:04Z

EXERCISE ONE

← Older revision		Revision as of 03:53, 13 June 2010
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	I can think of at least six ways of doing this, how about you?		I can think of at least six ways of doing this, how about you?

			Below are the various examples I came up with, and running times using an input file with 1.5 million blank lines and 3 million non-blank lines. You can generate these statistics by preceding the command with 'time -p'.

			# First example from <http://www.vectorsite.net/tsawk_3.html>
			awk 'NF != 0 { ++count } END { print count }' filename
			3000000
			real 3.67
			user 3.55
			sys 0.10

			awk '/./ { ++count } END { print count }' filename
			3000000
			real 2.96
			user 2.81
			sys 0.12

			time -p grep -c . filename
			3000000
			real 0.94
			user 0.84
			sys 0.08

			# sed is just a slower grep here.
			sed -n -e '/./p' filename \| wc -l
			real 6.00
			user 5.64
			sys 0.14
			3000000

			# If you REALLY love sed, you can replace wc -l, too!
			sed -n -e '/./p' filename \| sed -n -e '$='
			real 7.43
			user 5.70
			sys 0.19
			3000000

			tr -s '\012' < filename \| wc -l
			real 1.21
			user 0.84
			sys 0.13
			3000000

			# -b and -s are non-POSIX extensions to cat found on GNU and
			# BSD systems.
			cat -b -s filename \| tail -n 2 \| cut -f 1
			real 1.20
			user 0.63
			sys 0.16
			2999999
			3000000

			sh -c 'count=0
			while read ln ; do
			[ -n "$ln" ] && count=$(($count+1))
			done
			echo $count' < filename
			3000000
			real 240.14
			user 214.12
			sys 24.96

			perl -e 'while (<>) { chomp; if ($_) { ++$count } } ;
			print "$count\n"' < filename
			3000000
			real 7.22
			user 7.00
			sys 0.14

			perl -e 'while (<>) { if (/./) { ++$count } } ;
			print "$count\n"' < filename
			3000000
			real 8.93
			user 8.78
			sys 0.11

			# This one displays a separate count of blank, non-blank, and
			# total lines.
			awk 'NF != 0 {++nonblank} NF == 0 {++blank}
			END {print "Non-blank:",nonblank ; print "Blank:",blank ;
			print "Total:",NR}' filename
			Non-blank: 3000000
			Blank: 1500000
			Total: 4500000
			real 5.42
			user 5.28
			sys 0.12

			# Actually, we don't need a separate pattern and action to
			# count blank lines; we can subtract from the total instead.
			awk 'NF != 0 {++count}
			END {print "Non-blank:",count ; print "Blank:",NR-count ;
			print "Total:",NR}' filename
			Non-blank: 3000000
			Blank: 1500000
			Total: 4500000
			real 3.75
			user 3.64
			sys 0.09

			# This does the same, but has to read the file three separate
			# times. On your system, might be faster or slower than the
			# one above; depends on whether CPU or I/O is the bottleneck.
			sh -c 'printf "Non-blank: " ; grep -c . filename ;
			printf "Blank: " ; grep -v -c . filename ;
			printf "Total: " ; wc -l filename \| cut -d " " -f 1'
			Non-blank: 3000000
			Blank: 1500000
			Total: 4500000
			real 2.25
			user 1.91
			sys 0.31

	=== EXERCISE TWO ===		=== EXERCISE TWO ===

Vance: /* Speaker/Presentation */ change to replacement topic

2010-06-12T04:53:30Z

Speaker/Presentation: change to replacement topic

@@ Line 9: / Line 9: @@
 == Speaker/Presentation ==
-David Kraus, Sr. Automation Engineer at [http://www.isquaredt.com Integrated Industrial Technologies, Inc.], will be giving a presentation on [http://en.wikipedia.org/wiki/OPC_Unified_Architecture OPC-UA] and its implementation by [http://www.inductiveautomation.com/products/ignition Ignition] from [http://www.inductiveautomation.com/ Inductive Automation].
+[[User:Vance|Vance Kochenderfer]] will be talking a bit about the UNIX text processing utilities such as grep, sed, awk, cat, wc, and the like.
-OPC-UA expands into the title Object Linking and Embedded (OLE) for Process Control Unified Architecture.  OPC is an open standard for data exchange originally developed by Microsoft and maintained by the OPC Foundation.  It is based the aging OLE, COM, and DCOM technologies.  The recent OPC-UA specification provides means to develop cross-platform implementations of OPC.
+However, you don't get to just sit on your butt and listen; this is an audience-participation event.  What we're going to do is take a couple simple tasks, and then explore how you could accomplish them using various UNIX utilities.
-While OPC-UA and Ignition are not open source, they are cross-platform and supported on Linux and Microsoft Windows alike.
+The goal is not solely to find the standard, quickest, or simplest solution, but to try out as many different whacked-out options as we can.  So don't stop thinking once you've got an answer, even if it's a good one - see what else you can come up with!
 == Meeting Minutes ==

Curlynoodle: /* Speaker/Presentation */

2010-06-10T22:58:49Z

Speaker/Presentation

← Older revision		Revision as of 22:58, 10 June 2010
Line 9:		Line 9:
	== Speaker/Presentation ==		== Speaker/Presentation ==

	(~~TBA~~)		David Kraus, Sr. Automation Engineer at [http://www.isquaredt.com Integrated Industrial Technologies, Inc.], will be giving a presentation on [http://en.wikipedia.org/wiki/OPC_Unified_Architecture OPC-UA] and its implementation by [http://www.inductiveautomation.com/products/ignition Ignition] from [http://www.inductiveautomation.com/ Inductive Automation].

			OPC-UA expands into the title Object Linking and Embedded (OLE) for Process Control Unified Architecture. OPC is an open standard for data exchange originally developed by Microsoft and maintained by the OPC Foundation. It is based the aging OLE, COM, and DCOM technologies. The recent OPC-UA specification provides means to develop cross-platform implementations of OPC.

			While OPC-UA and Ignition are not open source, they are cross-platform and supported on Linux and Microsoft Windows alike.

	== Meeting Minutes ==		== Meeting Minutes ==

Curlynoodle: /* Meeting Staff */

2010-06-08T12:51:42Z

Meeting Staff

← Older revision		Revision as of 12:51, 8 June 2010
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	* Host: Your name here		* Host: Your name here
	* Co-Host: Your name here		* Co-Host: Your name here
	* Donuts/Bagels: ~~Your name here~~		* Donuts/Bagels: [[User:curlynoodle\|David Kraus]]
	* Setup: ~~Your name here~~, Your name here		* Setup: [[User:curlynoodle\|David Kraus]], Your name here
	* Clean Up: ~~Your name here~~, Your name here		* Clean Up: [[User:curlynoodle\|David Kraus]], Your name here

	== Carpooling ==		== Carpooling ==

Vance: New page: WPLUG will have a General User Meeting and presentation on Saturday, June 12th, 2010, starting at 11am at the Wilkins School Community Center. == Schedule for the Day == 10:30am - Doo...

2010-05-22T05:08:43Z

New page: WPLUG will have a General User Meeting and presentation on Saturday, June 12th, 2010, starting at 11am at the Wilkins School Community Center. == Schedule for the Day == 10:30am - Doo...

New page

WPLUG will have a General User Meeting and presentation on Saturday, June 12th, 2010, starting at 11am at the [[Wilkins School Community Center]].

== Schedule for the Day ==
10:30am - Doors open, set up<br/>
11:00am - Business Meeting starts<br/>
11:30am - Featured Presentation<br/>
12:30pm - Meeting ends, everyone out. We are likely to go to [http://www.regentsquare.net/ds6pax.html D's 6pack] or [http://www.square-cafe.com/ Square Cafe] for lunch.<br/>

== Speaker/Presentation ==

(TBA)

== Meeting Minutes ==

(TBA)

== Meeting Staff ==
If you would like to volunteer to assist with this meeting, please add your name to one or more of the [[MeetingChecklist|categories]] below.
* Host: Your name here
* Co-Host: Your name here
* Donuts/Bagels: Your name here
* Setup: Your name here, Your name here
* Clean Up: Your name here, Your name here

== Carpooling ==

* Your name/location here

[[Category:Meetings]]
[[Category:Minutes]]