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Old 10-25-2012, 06:16 PM   #1
MidwestProduct
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Registered: Sep 2012
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Is bash being bipolar? Permission allowed, then denied


I'm sure this question comes up a lot, but I'm particularly confused in this situation.

I can run my program once, just fine. However, if I try to run it again without recompiling, bash refuses to give me permission. I have a small idea why, but I don't think think I'm right.

Here's what I'm doing (for a course assignment). I have a program that has to change itself during runtime. The easiest way I thought to do this would be to to add blank lines to the executable, by creating a file with a few "\n" in them, and then concatenating them using a system call. It works! But only once.

However, if I manually go through and add a new line to the .exe and run it, it never stops me. I don't need to recompile...which is weird.

My thought was that maybe bash thinks I'm up to something...and wants to stop it, which also is understandable. However, I'm just doing my homework, so I hope this isn't the case.

Could anyone shed some light on this matter? Does changing the executable, even if it doesn't hinder its ability to run, cause some problem or issue with permissions?
 
Old 10-25-2012, 06:37 PM   #2
chrism01
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Registered: Aug 2004
Location: Sydney
Distribution: Centos 6.8, Centos 5.10
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Show the cmds exactly and
Code:
ls -l
on the files (lowercase L there).
I suspect in the 'auto' case, you are concatenating in such a way that you end up with a new file and the default on file creation is no executable perms.

PS: as you are doing a course, here are some very good refs
http://rute.2038bug.com/index.html.gz
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/

Last edited by chrism01; 10-25-2012 at 06:38 PM.
 
1 members found this post helpful.
Old 10-25-2012, 08:26 PM   #3
MidwestProduct
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Registered: Sep 2012
Posts: 6

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Why didn't I think of that! That is exactly what the problem is. Thank you!
 
Old 10-25-2012, 11:49 PM   #4
chrism01
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Registered: Aug 2004
Location: Sydney
Distribution: Centos 6.8, Centos 5.10
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That's why you are doing the course
 
  


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