[NTLUG:Discuss] Interesting bash shell scripting

[Eric Waguespack]

you don't need to do command substitution:

for x in *.rar; do unrar e "$x"; done

On Wed, Mar 11, 2009 at 6:13 PM, Kevin Lee <klee24 at gmail.com> wrote:
> I've run into this many times.  I believe the problem with
>
> for i in `ls -1`;do unrar x "$I"; done
>
> is your IFS variable. By default IFS is a space and/or newline.  Because the
> file had a space in the name, bash interpreted the file name as 2 separate
> values.  I suspect that your original script would work as expected if you
> did this:
>
> export IFS=$'\n'
> for i in `ls -1`;do unrar x "$I"; done
>
> Be careful though, modifying the IFS might have unintended consequences
> later on in the script. You may want to save it before the loop and restore
> it after the loop, or you could just use Chris' suggestion and use ls -Q =)
>
>
>
> On Wed, Mar 11, 2009 at 5:37 PM, Daniel Hauck <daniel at yacg.com> wrote:
>
>> Just thought I'd take a moment to share something I learned.
>>
>> I have this folder with a set of RAR archive files and I wanted to
>> extract them but they are large and it consumes time to use a GUI.  So I
>> decided I wanted to use the command line in some way that makes sense.
>> Unfortunately, I can't just say "unrar x *.rar" because unrar doesn't
>> like this.
>>
>> So I thought "use a for loop!"  And I tried this:
>>
>> for i in `ls -1` ; do unrar x "$i" ; done
>>
>> But that didn't quite yield what I was after as it did weird things in
>> the presence of filenames with spaces in them... and yes, these files
>> have spaces in the names.  So what next?
>>
>> bash's "read" should be able to read a line into a variable and handle
>> spaces just fine!  So I did this:
>>
>> ls -1 | for i in read ; do unrar x "$i" ; done
>>
>> This also had problems.
>>
>> Finally I did a little googling and found this:
>>
>> ls | while read f ; do unrar x "$f" ; done
>>
>> The while loop worked better than the for loop.  I am unsure why that is
>> the case exactly but I am sure Chris will be able to offer a better
>> analysis of the problem and the solutions.  But this technique is rather
>> useful so I thought I would share.
>>
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>>
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