What does this command do?

[root@fackamato-laptop ~]# dd if=/dev/zero of=/dev/null bs=1M count=100000
100000+0 records in
100000+0 records out
104857600000 bytes (105 GB) copied, 10.5889 s, 9.9 GB/s
[root@fackamato-laptop ~]# dd if=/dev/zero of=/dev/null bs=1M count=100000
100000+0 records in
100000+0 records out
104857600000 bytes (105 GB) copied, 25.8666 s, 4.1 GB/s
[root@fackamato-laptop ~]# dd if=/dev/zero of=/dev/null bs=1M count=100000
100000+0 records in
100000+0 records out
104857600000 bytes (105 GB) copied, 16.213 s, 6.5 GB/s
[root@fackamato-laptop ~]#
I know, I mean it reads zeroes into /dev/null in 1MB chunks, but how does it work? What generates the zeroes? Fluctuation is probably because of cpufreq. Is it only cpu-bound or is it memory speed bound too? Just curious...

Cool, this gave me my first occasion to try and understand something in the kernel sources.
From what I've seen, the driver that manages /dev/zero simply puts all zeroes in the char* output buffer it's passed (actually using an asm routine for it, so it's probably as efficient as can be). Piping to /dev/null pretty much does nothing at all.
I can't really follow the call stack to those functions but it's pretty certain it totally bypasses the I/O subsystem.
As for experimental data, dding from zero to null on my machine maxes out my cpu usage and the throughput only depends on cpu availability.
Last edited by Arkane (2009-02-18 21:14:27)

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What does this command do? "$HOME/path/to/the/Folder/"

Hi,
What does the following command do?
$HOME/path/to/the/Folder/TEMP
If the TEMP file does not exist, will it create a new TEMP folder?
How can I check whether a "new TEMP folder" is created?
Thanks in advance.
Ed

So "$HOME/path/to/the/Folder/.DS_Store" will fill in the "path" that the .DS_Store is stored?
You fill in the path. That is to say, we do not know the folder you are interested in. And since there are thousands of folders (hundreds of thousand) on the Mac, the computer will not fill it in either. ONLY "You" know where the folder you are interested in lives. So you replace "path/to/the/Folder" with the correct information. Until then "path/to/the/Folder" is a place holder, and a way for me to give you the general idea of how to specify the path, without my actually knowing where the desired folder lives.
You build a path by stringing folder names together, separated by a forward slash / and if there are any spaces or punctuation characters in the folder names, you protect the full path name by enclosing it in quotes, 'stuff to protect goes in here'.
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BTW, is it right that the "." will make the file "hidden"?
A file with a leading period in its name is a long standing convention from back in the '70's on Unix platforms that by default the 'ls' (list) command would not display files that started with a leading period unless' ls -a' was used. This was a way to put config files in a users home directory, but not clutter up the 'ls' output with things most users did not care about on a day-to-day basis. Over time, it was adapted as a way to hid files. The Mac "Finder" took up treating files with leading periods as hidden files.
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Can I check whether the directory or file exist from the Finder -> Mac HD or Finder -> Home?
If the file or folder does not have a leading period or the above mentioned hidden file attribute, the Finder can display, if you can navigate to the file or folder. Finder -> Go -> "Go to Folder..." can get you anywhere, assuming you can enter the /path/to/where/you/want/to/go/notation, or at least the beginning to get you started. Just entering / all by itself will put you at the top of the file system (called the root directory).
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Pls. what does this command mean?

sudo rm -rf /System/Library/Extensions/IOPlatformPluginFamily.kext
Someone left a post on another site and claims this will stop the whine on the MacBook Pros.
Okay, I got desperate, I pasted it on my terminal and rebooted as indicated and the whine is gone. I had the high pitch whine when running on battery only.
If this is bad, how do I reverse it? Did it correct the problem or did this command mask the problem? If so, can someone let me know how to reverse it? Thx
MBP 15" 2.0 Mac OS X (10.4.7)

Thanks for the responses.
Yes, it was dumb to do that. Luckily, there are people out there that are not maliclious but he/she should of indicated that I should save the file first.
Go figure, I find this same revelation else where including the 'save' requirement, after the fact.
I did however recover the file that I deleted and the whine is back, thanks to Niel's suggestion. Nice program.
Temperature Monitor was showing Core's at 72 C and now both at 54 after reinstalling the deleted file. The MBP was running very hot which bothered me although the whine did disappear but I was afraid of what this heat would do to its innerds if it continued.
I've only had the MBP for 3 days and am torn if I should return for a refund and wait or live with the whine and use QuietMBP or Photobooth.
Well, I'll play some more and decide by Friday.
Cheers all.
MBP 15" 2.0 Mac OS X (10.4.7)

What does this error message mean and how do I solve it? "Sorry, one or more of the following command-line tools was not found: /usr/bin/lsbom, /bin/pax, /bin/mkdir, /bin/chmod, or /usr/bin/update_prebinding."

When I try to open up this program, Pacifist, I receive this error message. Here's a screenshot. http://i.imgur.com/v717w.jpg What does this error message mean and how do I solve it?

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Images have ? symbol on the top right corner of the thumbnail what does this mean and how do I remove it?

Q - My images have a
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A tutorial demonstrating above can be found
Here

Q - My images have a
? symbol on the top right corner of the thumbnail what does this mean and how do I remove it?
A - The
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OK.
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A tutorial demonstrating above can be found
Here

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My MacBook has a grey screen with a folder and a question mark in the middle what does this mean?

My MacBook has a grey screen with a folder and a question mark in the middle what does this mean?

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If you have Snow Leopard:
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Download and install Mac OS X 10.6.8 Update Combo v1.1.
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Reinstall Lion, Mountain Lion, or Mavericks without erasing drive
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Repair
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Reinstall Mountain Lion or Mavericks
OS X Mavericks- Reinstall OS X
OS X Mountain Lion- Reinstall OS X
OS X Lion- Reinstall Mac OS X
Note: You will need an active Internet connection. I suggest using Ethernet
if possible because it is three times faster than wireless.

HT5622 What does this mean? "can't get email being used by another device."

What does this mean? "can't get email being used by another device."

Goto Finder > Help > type in Trash...
From Finder Help Trash...
" Empty the Trash
Command (⌘)-Shift-Delete
Empty the Trash without any warning or when it contains locked files
Command (⌘)-Shift-Option-Delete
Hold down the Option key, and then choose Finder > Empty Trash "
See here
http://support.apple.com/kb/HT1526
http://www.thexlab.com/faqs/trash.html

I have a cirlce with a line through it at startup. What does this mean?

I have a circle with a line through it at boot up. What does this mean?

It means that there is no bootable disk found. This
could be either a totally corrupted disk or a hardware
failure.
If you were running OSX 10.7 or 10.8, you could try booting
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What does this" touch /var/lock/subsys/oracle9i " used for?

touch /var/lock/subsys/oracle9i
this is in oracle auto start scripts.
What does this" touch /var/lock/subsys/oracle9i " used for?
Thanks.

ok,
this touch in dbora is solely used for dbora. The dbora script will later on remove the file after stop database.
sample of dbora
#!/bin/bash
# chkconfig: 35 99 10
# description: Starts and stops Oracle processes
# Set ORA_HOME to be equivalent to the $ORACLE_HOME
# from which you wish to execute dbstart and dbshut;
# Set ORA_OWNER to the user id of the owner of the
# Oracle database in ORA_HOME.
ORA_HOME=<Type your ORACLE_HOME in full path here>
ORA_OWNER=<Type your Oracle account name here>
case "$1" in
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       if [ -f $ORA_HOME/Apache/Apache/bin/apachectl ]; then
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          su - $ORA_OWNER -c "$ORA_HOME/Apache/Apache/bin/apachectl stop"
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esac
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I have downloaded a movie to rent from iTunes but it is giving me an error message 5103. What does this mean?

I have downloaded a movie to rent from iTunes but it is giving me an error message 5103. What does this mean?

The fix for this is supposed to be resetting the system clock to automatic time, but this, as we've seen, more often than not fails to work. After a bit of an email exchange between Apple support and myself I discovered the true fix for this issue, or at least, the one that they said to use and that worked for me.
After resetting your clock go to the folder /Users/Shared in Finder and delete the folder "SC Info". This is a hidden folder, so the way you will need to get it to appear is to use the go to folder command (Shift + Command + G) and type in /Users/Shared/SC Info and hit enter. Change to the column view and you'll be able to see the folder there. Move it to the trash and it will go away, and take your problems with it. Restart the computer for the deletion to take effect and then reauthorize your itunes. Should play your rentals after that.
Props to Zarchanalin for the answer!

What does this error message mean: "Filename: Mips32.ari TFTP Error: 'File not found' in AP-105"?

Question: What does this error message mean: "Filename: Mips32.ari TFTP Error: ‘File not found’ in AP-105"?
Product and Software: This article applies to AP-105.
The root cause of this error is that the AP cannot perform a code upgrade.
Scenario 1
Check the ArubaOS code.
The minimum requirement to bring up an AP-105 is ArubaOS 3.3.3+ or ArubaOS 3.4.1+.
If the controller is running pre 3.3.3 code, upgrade the code to fix the issue.
Scenario 2
If the AP is not connected to the controller directly, bring up the AP in the controller and then connect it to the desired location. This process loads mips32.ari to the AP so that the AP can upgrade the code.
Scenario 3
The AP has no power adapter and you want to use the PoE feature. A few controller series like the 200 and 3000 Series do not support PoE. In this case, the AP cannot be terminated physically in the controller. Instead, connect the AP to the PoE switch, which is connected to the controller. Then assign a static IP configuration for the AP using the following commands:
apboot> setenv ipaddr <ip address>
apboot> setenv netmask <netmask>
apboot> setenv gatewayip <ip address of the gateway>
apboot> setenv master <ip address of the master>
apboot> setenv serverip <ip address of the TFTP server>
apboot> setenv bootcmd tftp
apboot> save
apboot> boot
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I want to download this file Mips32.ari for AP-105 device. Please give me this file download link. APBoot 1.2.4.4 (build 26618)
Built: 2011-01-07 at 13:42:04Model: AP-10x
CPU: AR7161 revision: A2
Clock: 680 MHz, DDR clock: 340 MHz, Bus clock: 170 MHz
DRAM: 128 MB
POST1: passed
Copy: done
Flash: 16 MB
PCI: scanning bus 0 ...
dev fn venID devID class rev MBAR0 MBAR1 MBAR2 MBAR3
00 00 168c 0029 00002 01 10000000 00000000 00000000 00000000
01 00 168c 0029 00002 01 10010000 00000000 00000000 00000000
Net: eth0
Radio: ar922x#0, ar922x#1Hit <Enter> to stop autoboot: 0
Checking image @ 0xbf100000
Invalid image format version: 0xffffffff
Checking image @ 0xbf800000
Invalid image format version: 0xffffffff
eth0 up: 1 Gb/s full duplex
DHCP broadcast 1
DHCP IP address: 192.168.x.xx
DHCP subnet mask: 255.255.255.0
DHCP def gateway: 192.168.x.xx
DHCP DNS server: 192.168.x.xx
DHCP DNS domain: xx
ADP multicast 1
ADP broadcast 1
ADP multicast 2
checksum bad
ADP broadcast 2
checksum bad
ADP multicast 3
checksum bad
checksum bad
checksum badRetry count exceeded
DNS request 1 for aruba-master to 192.168.x.xx
checksum bad
checksum bad
checksum bad
T Using eth0 device
TFTP from server 192.168.x.xx; our IP address is 192.168.x.xx
Filename 'mips32.ari'.
Load address: 0x2000000
Loading: checksum bad
T T checksum bad
T checksum bad
checksum bad
checksum bad
T checksum bad
checksum bad
T T checksum bad
T checksum bad
checksum bad
T T T
Retry count exceeded; starting again
eth0 up: 1 Gb/s full duplex
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum badARP Retry count exceeded; starting again
eth0 up: 1 Gb/s full duplexchecksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad ThanKs :)

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I found the manual update, which worked!
http://www.adobe.com/support/downloads/thankyou.jsp?ftpID=5595&fileID= 5604

Hi Barbara,
For failed 13.1.2 update error U44M1P7, Please refer to the solution mentioned in the following threads :
http://forums.adobe.com/message/5396792#5396792
http://forums.adobe.com/message/5409050#5409050

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Thanks for your reply LexSchellings, There is no disc in the drive and I went through the suggestions you put forward on the phone with Apple support without any luck. I can put a disc in but it pops straight back out again without registering on finder.
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When trying to update my IPad apps I am getting the message "Your Apple ID has been disabled". Still have more than 50$ in my account, so what does this mean ? What can I do to get my ID enabled again ?

when I am trying to download IPad updates I get the message "Your Apple ID has been disabled". What does this mean? How do I get my ID enabled again? Still got more than 50$ in my account !

Reset your Apple ID password here > Apple - My Apple ID
More information here > Apple ID: "This Apple ID has been disabled for security reasons" appears

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