[NTLUG:Discuss] Linux script question

[Pervaz Allaudin]

I appreciate the concern of both of yous; I do have the source in a zip 
form the opensource so I can bring it back if needed.
I have experience in the other OS and have done my stupi... eh hum.. 
experience giving mistakes.

pervaz


Bug Hunter wrote:

>On Mon, 16 Jun 2003, Rusty Haddock wrote:
>
>  
>
>>Bug Hunter wrote:
>>    
>>
>snip>     >> > 
>  
>
>>    >
>>    >  for a single file:
>>    >
>>    >  sed /oldtext/newtext/ filename > filename.newfile
>>    >  rm -f filename
>>    >  mv filename.newfile filename
>>    >
>>    >  
>>    >in bash
>>    >
>>    >  for i in /dirname/*
>>    >do
>>    > sed /oldtext/newtext/ $i > $i.newfile
>>    > rm -f $i.newfile
>>    > mv $i.newfile $i
>>    >done
>>
>>Be careful here!!!  I see two problems here:
>>	1) Why are you nuking the .newfile you just created???
>>	   Just delete the 'rm' command.
>>    
>>
>
> yep.
>
>
>  
>
>>	2) If the 'sed' script fails you're still gonna nuke your
>>	   old files!!!  How would 'sed' fail?  Oh, a full file
>>	   system for one way.  There are others.  "Been there,
>>	   lost that!"  One of the better things to do is to join
>>	   the 'mv' to the 'sed' with a '&&'.  This way, if the
>>	   'sed' fails you don't do the 'mv'.  For example:
>>	   	
>>    	sed /oldtext/newtext/ $i > $i.newfile && mv $i.newfile $i
>>
>>    
>>
> good idea
>
>
>  
>
>>	    Remember that the SHELL is the one who will create the
>>	    .newfile, not the 'sed' command.  It is created before
>>	    the 'sed' program is even run -- it has to be otherwise
>>	    'sed's stdout won't be connected to anything.
>>
>>    >  This was given to me by a fellow named Richard a while back. :)
>>
>>Be caseful what Richard tells you for now on. :-)  Yes, it'll work
>>(well, remove the 'rm' like) 99.9% of the time.  Alas, 0.1% of the
>>time it will lose what you spent 99.9% of the time creating! :-(
>>
>>    
>>
>
>  Well, a loaded gun in the wrong hands.....
>
>
>  I always make a copy of the directory and run it on the copy until I'm 
>happy.  Then I move the original to a backup directory, and move the copy 
>to the original, if possible.  (sometimes a reboot or restart of the 
>demon is required.)
>
>  Discretion is the better part of system administration.  Or is that 
>valor?
>
>   I had *assumed* intelligence on the other side.  Also had assumed that 
>if they had not been there, done that, they would soon learn and never do 
>it twice.  Or in my case, the third time is the charm. <grin>
>
>bug
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