Re: [PLUG] Easy Bash Scripting Question

[bergman@merctech.com]

In the message dated: Wed, 23 Dec 2009 08:32:57 EST,
The pithy ruminations from Casey Bralla on 
<Re: [PLUG] Easy Bash Scripting Question> were:
=> On Wednesday December 23, 2009 8:28:01 am bergman@merctech.com wrote:
=> 
=> Good point, Mark, but this script was just an example.  (My script is more 
=> complex and does a specific task unrelated to the question I was asking.)

Um, I don't mean to be rude, but if you're asking such an elementary question[1]
then I strongly doubt whether you should be running a "more complex" 
script. Again, I'd suggest turning all the irreversible actions of the script 
(cp, rm, etc.) into "echo" statements until it's fully tested.

=> 
=> BTW, what does "sudo rm /* -r" do?  <grin>

Um, under what OS? Under what distro or version of "rm"[2]? Depending on the
verion of "rm", it'll [try to] remove all files in the root directory, followed
by trying to remove a file name "-r" in the current directory. Or it's try to
recursively remove everything from the root directory down. Of course, without
the "-f" option, it may still fail[3] (even when run as root) on certain files
and directories.


Again, if you don't understand how things work, you won't get the results that 
you expect.


Mark


	[1] To be clear, there's nothing wrong with asking elementary questions
	...we all need to start somewhere, and it's better to ask than not to.
	
	[2] I don't have an embdedded machine here...how does busybox handle 
		options that follow the filename arguments?

	[3] man chattr setfacl. Research rbac.


=> 
=> > 
=> > =>
=> > => for example:
=> > =>
=> > => #!/bin/bash
=> > => cp file1 file2
=> > => mkdir /directory1
=> > => cd /directory1
=> > => rm *
=> > 
=> > Whoa! That's very risky....think of what happens if the "mkdir" or "cd"
=> > commands fail. I've seen developers wipe out a multi-millon dollar
=> > ecommerce site multiple times with just this kind of error. (Yes, multiple
=> > times...they assumed it was an OS or sysadmin error, and after I restored
=> >  the server--multiple times--they kept running the same script...loads of
=> >  fun.)
=> > 
=> > Before running this script, I'd strongly recommend:
=> > 
=> > 	changing the "rm" command to echo what it would do, as in:
=> > 
=> > 		echo "Would do: rm *"
=> > 
=> > 
=> > 	learning how to check the return value of a command (the mkdir & cd),
=> > 	and how to avoid doing the following operations if the command[s]
=> > 	failed
=> > 
=> > Mark
=> > > 
=> 
=> -- 
=> 
=> Casey Bralla
=> Chief Nerd in Residence
=> The NerdWorld Organisation
=> 
=> http://www.NerdWorld.org
=> ___________________________________________________________________________
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