Programming Forums > Script Programming > Bash / Shell Scripting

a thing · Aug 17th, 2006, 1:36 AM

I was looking back through the threads I started and came across http://programmingforums.org/forum/s...38&postcount=6. I thought that would be more accurate, so I've been trying to construct a function that prints the fastest domain from the list of domains given to it. So far I have:

(Toggle Plain Text)

#!/bin/sh

getmirror()
{
	declare -a averages #Make sure $averages doesn't get thrown away too soon by garbage collection.
	i=0
	for mirror; do
		averages[i]="$(ping -c 2 $mirror|tail -n1|cut -d/ -f5|cut -d. -f1)"
		i=$(expr $i + 1)
	done
	IFS="
" #So sort will count different elements of $averages as different values.
	bestaverage=$(echo "${averages[*]}"|sort -n|head -n1)
	size="${#averages[*]}"
	echo $bestaverage
	for (( i=0; "${averages[i]}" != "$bestaverage"; i++ )); do echo; done #The shell complains if there's nothing between do and ;done.
	echo $i
}

echo $(getmirror jaist.dl.sourceforge.net switch.dl.sourceforge.net easynews.dl.sourceforge.net)

My problems:
1. How would I reference the argument number $i? So if $i == 2, then reference $2. Like $$i, but that's not the correct syntax.
2. What's the best way to round a number? [ complains if there are decimals passed to it. cut -d. -f1 sort of works, but it isn't the most accurate.

a thing · Aug 23rd, 2006, 1:45 AM

Kabump.

DaWei · Aug 23rd, 2006, 9:08 AM

1. Sorry, not familiar with bash.
2. Presuming you mean round to the nearest integer, add .5 to the number, then floor it (truncate the decimals).

jim mcnamara · Aug 23rd, 2006, 4:38 PM

The print command line utility will round numbers.

(Toggle Plain Text)

z=2.111
printf "%.0f\n" $z

stick a :; between do and done That's a colon semicolon

Finally, I don't understand what you mean by reference $i. You want to get
the value of i outside the function? Or the value of the array element referenced by i - the array you declare inside the function?

Note: i only has scope during the "for" loop inside the getmirror function. The array "averages" only has scope inside the getmirror function.

They do not exist outside their scope.

a thing · Aug 23rd, 2006, 10:57 PM

Quote:

Originally Posted by jim mcnamara

The print command line utility will round numbers.

(Toggle Plain Text)

z=2.111
printf "%.0f\n" $z

Thanks, that worked. Now I have

(Toggle Plain Text)

averages[i]="$(printf "%.0f" $(ping -c 2 $mirror|tail -n1|cut -d/ -f5))"

DaWei, I'll remember that for other languages.

Quote:

Originally Posted by jim mcnamara

stick a :; between do and done That's a colon semicolon

That worked too

By the way, does : ever do anything?

Quote:

Originally Posted by jim mcmamara

Finally, I don't understand what you mean by reference $i. You want to get
the value of i outside the function? Or the value of the array element referenced by i - the array you declare inside the function?

Note: i only has scope during the "for" loop inside the getmirror function. The array "averages" only has scope inside the getmirror function.

They do not exist outside their scope.

1. See the comment on line 5.
2. Reread #1 in the first post. (If I referenced the array element referenced by $i I'd just get the best average, not the fastest domain.)

Meh, I gotta get used to going from 8 VDs to 12.

Oo 100 posts!

a thing · Sep 24th, 2006, 5:40 PM

I've got it! $(eval "echo $""$i")

Aug 23rd, 2006, 1:45 AM	#2
a thing Unverified User Join Date: Aug 2005 Location: none Posts: 146 Rep Power: 0	Kabump. __________________ Warning: My posts may change (dramatically) within the first 15 minutes they're posted. Got 'Nux?�GNU/Linux and other free software support. It's GNU/Linux, not just Linux.

Aug 23rd, 2006, 9:08 AM	#3
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	1. Sorry, not familiar with bash. 2. Presuming you mean round to the nearest integer, add .5 to the number, then floor it (truncate the decimals). __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Aug 23rd, 2006, 4:38 PM	#4
jim mcnamara Hobbyist Programmer Join Date: Jun 2005 Location: New Mexico Posts: 228 Rep Power: 4	The print command line utility will round numbers. (Toggle Plain Text) z=2.111 printf "%.0f\n" $z z=2.111 printf "%.0f\n" $z stick a :; between do and done That's a colon semicolon Finally, I don't understand what you mean by reference $i. You want to get the value of i outside the function? Or the value of the array element referenced by i - the array you declare inside the function? Note: i only has scope during the "for" loop inside the getmirror function. The array "averages" only has scope inside the getmirror function. They do not exist outside their scope.

Sep 24th, 2006, 5:40 PM	#6
a thing Unverified User Join Date: Aug 2005 Location: none Posts: 146 Rep Power: 0	I've got it! $(eval "echo $""$i") __________________ Warning: My posts may change (dramatically) within the first 15 minutes they're posted. Got 'Nux?�GNU/Linux and other free software support. It's GNU/Linux, not just Linux. Last edited by a thing; Sep 24th, 2006 at 5:55 PM.

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Aug 17th, 2006, 1:36 AM	#1
a thing Unverified User Join Date: Aug 2005 Location: none Posts: 146 Rep Power: 0	$$i and rounding I was looking back through the threads I started and came across http://programmingforums.org/forum/s...38&postcount=6. I thought that would be more accurate, so I've been trying to construct a function that prints the fastest domain from the list of domains given to it. So far I have: (Toggle Plain Text) #!/bin/sh getmirror() { declare -a averages #Make sure $averages doesn't get thrown away too soon by garbage collection. i=0 for mirror; do averages[i]="$(ping -c 2 $mirror\|tail -n1\|cut -d/ -f5\|cut -d. -f1)" i=$(expr $i + 1) done IFS=" " #So sort will count different elements of $averages as different values. bestaverage=$(echo "${averages[]}"\|sort -n\|head -n1) size="${#averages[]}" echo $bestaverage for (( i=0; "${averages[i]}" != "$bestaverage"; i++ )); do echo; done #The shell complains if there's nothing between do and ;done. echo $i } echo $(getmirror jaist.dl.sourceforge.net switch.dl.sourceforge.net easynews.dl.sourceforge.net) #!/bin/sh getmirror() { declare -a averages #Make sure $averages doesn't get thrown away too soon by garbage collection. i=0 for mirror; do averages[i]="$(ping -c 2 $mirror\|tail -n1\|cut -d/ -f5\|cut -d. -f1)" i=$(expr $i + 1) done IFS=" " #So sort will count different elements of $averages as different values. bestaverage=$(echo "${averages[]}"\|sort -n\|head -n1) size="${#averages[]}" echo $bestaverage for (( i=0; "${averages[i]}" != "$bestaverage"; i++ )); do echo; done #The shell complains if there's nothing between do and ;done. echo $i } echo $(getmirror jaist.dl.sourceforge.net switch.dl.sourceforge.net easynews.dl.sourceforge.net) My problems: 1. How would I reference the argument number $i? So if $i == 2, then reference $2. Like $$i, but that's not the correct syntax. 2. What's the best way to round a number? [ complains if there are decimals passed to it. cut -d. -f1 sort of works, but it isn't the most accurate. __________________ Warning: My posts may change (dramatically) within the first 15 minutes they're posted. Got 'Nux?�GNU/Linux and other free software support. It's GNU/Linux, not just Linux. Last edited by a thing; Aug 17th, 2006 at 1:50 AM.

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Programming Forums > Script Programming > Bash / Shell Scripting

$$i and rounding