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unix command needed

Posted on 2010-08-25
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Last Modified: 2013-12-06
I need a one line script to find the latest log filename that starts with 'System.out' from the current folder.


I need this because I am trying run the following  command  in putty

tail -100f  <need a one line script to find the latest log filename that starts with 'System.out' from the current folder>.log


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Question by:cofactor
10 Comments
 
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Expert Comment

by:MedinaExpert
ID: 33528316
tail -100f `ls -latr System.out* | cut -c 52- | tail -1`

You might have to change the 52- to adjust for you version of ls

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Expert Comment

by:MedinaExpert
ID: 33528334
This is actually better, sorry

tail -100f `ls -latr System.out* | tr ' ' '\n' | tail -1`
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Author Comment

by:cofactor
ID: 33528392
what is latr ?

what is  tr ?

why new line \n you are using ?

also there is a second tail you used ...why ?

This is a complex script . Could you please explain what it is doing ?  I'm not a Unix guy. So, could you please explain in simple way.
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Expert Comment

by:MedinaExpert
ID: 33528543
Sure, no drama :)

tail -100f  `ls -latr System.out* | tr ' ' '\n' | tail -1`


the part between ``s is executed as a command in a command
ls -latr means Long All sorted in Time Reverse (newest listed latest)
then we change all spaces for newlines (the tr command) and only take the last line (the tail command) wich contains the last System.out* file

Hope this helps...

Cheers
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Accepted Solution

by:
Tintin earned 50 total points
ID: 33528745
No need to over complicate it.  Just do

ls -t System.out* | tail -1

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Expert Comment

by:MedinaExpert
ID: 33528762
true, but make it ls -t | head -1 or ls -tr | tail -1 to get the newest.
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Author Comment

by:cofactor
ID: 33529085
>>>No need to over complicate it.  Just do
ls -t System.out* | tail -1

does it  show the latest ?
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Assisted Solution

by:MedinaExpert
MedinaExpert earned 50 total points
ID: 33529093
ls -tr System.out* | tail -1
or
ls -t System.out* | head -1

will show the newest file
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Author Comment

by:cofactor
ID: 33529443
ok . I have little doubt still
>>>ls -t System.out* | head -1
Here is my understanding

ls -t  System.out*  =  list files that started with  'System.out'  sorted by last modification time.
Now, head -1  = show  first file from the beginning  of the list of files.
and "|"  is the connector  which  sends  the file list  to on which head works
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Expert Comment

by:ozo
ID: 33529548
that's correct
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