Re: how to extract exact text

On Thu, 19 Sep 2013 13:29:59 +0200, "MOKRANI Rachid"
<[email protected]> wrote:

> Other text [bug 5] hardware
> 
> [bug 256] my software
> 
> My text [bug 1256] 
> 
>  
> 
> How can I extract only the text 
> 
> [bug 5]
> 
> [bug 256]
> 
> [bug 1256]
> 
>  
> 
>  
> 
> The text I need to extract is always [bug XXXXX] 
> 
> XXXX is always different number.

The answer depends on whether there can be multiple occurrences of [bug
XXX] on the same line. If not, it is trivially done with

sed -n 's/.*\(\[bug [0-9]*\)\].*/\1/p' test.txt

If not, the solution is more complex. A solution using \x1 as marker (needs
GNU sed), which also works in the single-occurrence case:

s/\[bug [0-9]*\]/\x1&/g
t ok
d
:ok
s/^[^\x1]*\x1//
s/\(\[bug [0-9]*\]\)[^\x1]*/\1/g
s/\x1/\n/g

In this case it's probably easier to use GNU grep, eg

grep -Eo '\[bug [0-9]+\]' test.txt

or awk or perl, eg

gawk -v RS='\\[bug [0-9]+\\]' 'RT{print RT}' test.txt

perl -ne 'print "$_\n" for (/\[bug \d+\]/g)' test.txt

-- 
D.