[debbugs-tracker] bug#18377: closed (piping output through egrep -- escaping of "+" only needed sometimes. Why?)

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Your message dated Mon, 01 Sep 2014 01:05:51 -0700
with message-id <address@hidden>
and subject line Re: bug#18377: piping output through egrep -- escaping of "+" 
only needed sometimes. Why?
has caused the debbugs.gnu.org bug report #18377,
regarding piping output through egrep -- escaping of "+" only needed sometimes. 
Why?
to be marked as done.

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18377: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=18377
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> Subject: 
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> piping output through egrep -- escaping of "+" only needed sometimes. Why?
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> Date: 
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> Sun, 31 Aug 2014 19:07:48 -0700
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> Hi all,
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> I'm trying to pipe of output of a command through egrep.
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> If I do this
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>         ldconfig -p | egrep "libstdc++"
>                 libstdc++.so.6 (libc6,x86-64) => /usr/lib64/libstdc++.so.6
>                 libstdc++.so.6 (libc6) => /usr/lib/libstdc++.so.6
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> that *IS* the answer I expect.
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> But if I simply add a ".so" to the egrep target, it returns nothing
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>         ldconfig -p | egrep "libstdc++.so"
>                 (empty)
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> If I *escape* the two "+", it works again.
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>         ldconfig -p | egrep "libstdc\+\+.so"
>                 libstdc++.so.6 (libc6,x86-64) => /usr/lib64/libstdc++.so.6
>                 libstdc++.so.6 (libc6) => /usr/lib/libstdc++.so.6
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> Why do I need to escape the "+" in the last case, but not in the first?
>
> Terry
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> --- End Message ---
> --- Begin Message ---
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> Subject: 
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> Re: bug#18377: piping output through egrep -- escaping of "+" only needed sometimes. Why?
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> Date: 
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> Mon, 01 Sep 2014 01:05:51 -0700
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> User-agent: 
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> Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0
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> address@hidden wrote:
> > Why do I need to escape the "+" in the last case, but not in the first?
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> Because "+" is a special character to egrep.  The pattern "libstdc++" is 
> equivalent to the pattern "libstdcc*" which matches in the first case, 
> whereas the pattern "libstdc++.so" is equivalent to the pattern 
> "libstdcc*.so" which does not match in the last case.
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>
> --- End Message ---