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Old 01-09-2009, 02:49 PM   #1
BeholdMyGlory
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Registered: Jan 2009
Posts: 1

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Regex in bash?


Say I have a string conatining a few words:
STRING="one two three four five six seven";

how do I go about removing the first three words? I've search google but not yet found anything that seems to do what I want.

I would like to use the following regex:
"[^ ]* [^ ]* [^ ]* "
As demonstrated i Java:
Code:
String string = "one two three four five six seven";
string = string.replaceFirst("[^ ]* [^ ]* [^ ]* ","");
System.out.println(string)
I've tried
echo ${STRING/[^ ]* [^ ]* [^ ]* /}
but that just gives me the very last word.
 
Old 01-09-2009, 04:30 PM   #2
antegallya
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Registered: Jun 2008
Location: Belgium
Distribution: Debian
Posts: 109

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Hello,
it is simply because the substring replacement you are using is expanding to the longest match. (Maybe what you do isn't what you mean, the '*' in bash doesn't mean the same as the '*' in java's regexp or others. Bash's '*' means expanding to any string of any character and it doesn't expand only the preceeding pattern)
Try using this instead :
Code:
${STRING#[^ ]* [^ ]* [^ ]* }
the '#' is for deleting the following match, starting from the front of $STRING and matching the shortest match.
In java '${string#PATTERN}' would be something like
Code:
string.replaceFirst("^PATTERN","")
Regards,
antegallya

Last edited by antegallya; 01-09-2009 at 04:31 PM.
 
Old 01-10-2009, 03:26 AM   #3
openSauce
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Registered: Oct 2007
Distribution: Fedora, openSUSE
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^^ the above doesn't work for me. However you can use sed:

Code:
$ echo $STRING | sed 's/[^ ]* [^ ]* [^ ]* //'
four five six seven
Type info sed to find out how it works.

Edit: actually antegallya's works too, just had a typo before

Last edited by openSauce; 01-10-2009 at 03:28 AM.
 
Old 01-10-2009, 07:30 AM   #4
archieval
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Location: Philippines
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u can also use perl, its a practical extraction =)
 
Old 01-10-2009, 08:32 AM   #5
colucix
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Registered: Sep 2003
Location: Bologna
Distribution: CentOS 6.5 OpenSuSE 12.3
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Or just use cut
Code:
$ string="one two three four five six seven"
$ echo $string
one two three four five six seven
$ string=$(echo $string | cut -d" " -f4-)
$ echo $string
four five six seven
 
  


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