"egrep 'libstdc++'" is taken as "egrep 'libstd(c+)+'", although I don't see that this behaviour is clearly defined in POSIX. Therefore, as Paul says, it's synonymous with 'libstdc(c*)'.
On Sun, 31 Aug 2014 19:07:48 -0700 terrygalant.li...@fastest.cc wrote: > Hi all, > > I'm trying to pipe of output of a command through egrep. > > If I do this > > ldconfig -p | egrep "libstdc++" > libstdc++.so.6 (libc6,x86-64) => /usr/lib64/libstdc++.so.6 > libstdc++.so.6 (libc6) => /usr/lib/libstdc++.so.6 > > that *IS* the answer I expect. > > But if I simply add a ".so" to the egrep target, it returns nothing > > ldconfig -p | egrep "libstdc++.so" > (empty) > > If I *escape* the two "+", it works again. > > 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 > > Why do I need to escape the "+" in the last case, but not in the first? > > Terry > >
