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Rabu, 13 Januari 2010

Unix Tip: REBOOTING BECAUSE OF FORK BOMBS

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2899 - January 13, 2010

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REBOOTING BECAUSE OF FORK BOMBS


There is nothing more frustrating for an Administrator who has to reboot system due to fork bomb

(the number of processes in the system reaches the maximum limit when a user, even a superuser, tries to execute some command, the system will respond with Vfork failed)

In Solaris under SPARC, this can be controlled by specifying a line in /etc/system

set maxuprc=64

And reboot the system. Now a user can have maximum of 64 processes under his ownership. By default the 'maxuprc' value is 16*maxusers - 5 where 'maxusers' is another tunable parameter in /etc/system

Caution : You should have a backup of /etc/system file before you make the changes. So that you can revert back to old system file using boot -a option in case of inconsistent system file.


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DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

Selasa, 12 Januari 2010

Unix Tip: WHAT TIME IS IT REMOTELY?

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2898 - January 12, 2010

http://www.ugu.com/sui/ugu/show?tip.today

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WHAT TIME IS IT REMOTELY?

To get time on a remote UNIX machine within the same domain, you can use the command:

% telnet 13

Trying ...
Connected to
Escape character is '^]'.
Fri Aug 27 19:20:27 1999
Connection closed by foreign host.

You can create a handy alias for the following command to get the remote time:

telnet 13 | grep :

This tip generously supported by: bhavin@informix.com

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==========================================================================
DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

Senin, 11 Januari 2010

Unix Tip: OUTAGE LENGTHS

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2897 - January 11, 2010

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OUTAGE LENGTHS

It is always good to give yourself enough time to perform an outage. One good rule is to use the simple formula: Length + 1/2 Length.

If your outage will take 1 hour call the outage for 1.5 hours.

If you outage will take 4 hours get a 6 hours window for the outage.

This will provide negotiating room with management, users, and time correct any issues that may develop from the outage.

How do you think Scotty, on Star Trek, was always able to get the engines back online early and look like a hero to Captain Kirk?


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==========================================================================
DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

Jumat, 08 Januari 2010

Unix Tip: WHAT FILE IS THAT IN?

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2894 - January 8, 2010

http://www.ugu.com/sui/ugu/show?tip.today

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WHAT FILE IS THAT IN?

Did you ever just want to know what files search patterns were in but didn't want to see the, search results?

Turn this:
$ grep quick *

story1.txt: The quick brown fox
story1.txt: The turtle was not quick.
recipe.txt: How to make soup quick.

Into this:
$ grep -l quick *

story1.txt
recipe.txt

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==========================================================================
DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

Kamis, 07 Januari 2010

Unix Tip: EDIT RUN EDIT

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2893 - January 7, 2010

http://www.ugu.com/sui/ugu/show?tip.today

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EDIT RUN EDIT

Here is a simple script that will edit a file, run it and edit it again. This is useful when you're doing alot of testing against a script.

Replace "file" with the name of the script.

------------- cut here ---------------
while [ 1 ]
do
vi file
clear; echo
chmod 755 file
./file
echo; echo -n "[pause] "
read pause
done


------------- cut here ---------------


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==========================================================================
DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

Rabu, 06 Januari 2010

Unix Tip: Who Owns an IP

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2892 - January 6, 2010

http://www.ugu.com/sui/ugu/show?tip.today

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Who Owns an IP

Here is how to find information about an ip owner

$ whois -h whois.arin.net 10.0.0.0


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==========================================================================
DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

Selasa, 05 Januari 2010

Unix Tip: SUM OF ALL THE DIGITS

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2891 - January 5, 2010

http://www.ugu.com/sui/ugu/show?tip.today

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SUM OF ALL THE DIGITS

Here is an easy way to calculate the sum of all the digits of a number:

$ expr `echo "987655" | sed -e 's/[0-9]/ + &/g' -e 's/^ +//g'`
40

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==========================================================================
DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

Senin, 04 Januari 2010

Unix Tip: REVERSE A FILE

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 2890 - January 4, 2010

http://www.ugu.com/sui/ugu/show?tip.today

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REVERSE A FILE

This commands will quickly reverse the listing of a file:

nl -ba FILE | sort -nr | cut -f2-


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==========================================================================
DISCLAIMER: All UNIX HOT TIPS ARE OWNED BY THE UNIX GURU UNIVERSE AND ARE
NOT TO BE SOLD, PRINTED OR USED WITHOUT THE WRITTEN CONSENT OF THE UNIX
GURU UNIVERSE. ALL TIPS ARE "USE AT YOUR OWN RISK". UGU ADVISES THAT
ALL TIPS BE TESTED IN A NON-PRODUCTION DEVELOPMENT ENVIRONMENT FIRST.

Unix Guru Universe - www.ugu.com - tips@ugu.com - Copyright 1994-2001
==========================================================================

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