Redirect the output of g++ compiler to a file?

Question

I see below messages while compiling an c++ program.

 test.cpp: In function ‘int main()’:
 test.cpp:950: error: no match for ‘operator<<’ in ‘std::cout << d->Derived::print()’
 /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/ostream:108: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]
 /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/ostream:117: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ios<_CharT, _Traits>& (*)(std::basic_ios<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]

I was thinking if I can redirect all these messages to an file and do not see anything on the console. I have tried redirecting stderr messages by

g++ test.cpp 2> xx

But this does not seems to work. I still see everything on the console and nothing inside the file.

Maybe related: https://stackoverflow.com/questions/578438/linux-g-compiler-redirect-stderr-and-stdout-creates-empty-file — Bob__, May 06 '20 at 08:23
Ignoring your reasons to do such thing, did you try `g++ test.cpp > xx`? It is possible that g++ writes these messages on stdout. Or you can use a shotgun approach `g++ test.cpp &> xx`. — Piotr Siupa, May 06 '20 at 08:24
Please clarify if you want to redirect the messages to *store* them of if you are trying to *hide* them. — Bob__, May 06 '20 at 08:25
@NO_NAME, I tried `g++ test.cpp > xx` and it did not work. I also tried to use shotgun approach 'g++ test.cpp &> xx' and it gave me an error sating 'Invalid null command' — Hemant Bhargava, May 06 '20 at 08:41
@Bob__, I am just trying to redirect everything on the screen to an file. No storage and no hiding. Just redirect. Thanks for coming by. — Hemant Bhargava, May 06 '20 at 08:42
For bash, `g++ test.cpp 2> xx` should work. You could redirect `stdout` too though: `g++ test.cpp > xx 2>&1` but I doubt that'll help since `g++` prints errors and warnings on `stderr`. — Ted Lyngmo, May 06 '20 at 08:43
@TedLyngmo, `g++ test.cpp > xx 2>&1` did not work. It says : `Ambiguous output redirect.` — Hemant Bhargava, May 06 '20 at 08:45
You are then running a `csh` type of shell. What does `echo $0` say? — Ted Lyngmo, May 06 '20 at 08:46
@TedLyngmo, I see. You are right. This is what I see: `echo $0 tcsh echo $SHELL /bin/bash ` — Hemant Bhargava, May 06 '20 at 08:50

score 5 · Accepted Answer · answered May 06 '20 at 08:47

5

For csh type of shells, do:

g++ test.cpp >& xx

answered May 06 '20 at 08:47

Ted Lyngmo

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Thanks Ted. So, this is shotgun approach to redirect everything. Does not matter if it is stderr, stdout or whatever, whatever is on the console would go to the xx. Is my understanding correct? – Hemant Bhargava May 06 '20 at 08:53
@HemantBhargava You are welcome! It redirects `stdout` and `stderr`. If the program somehow opens another stream to your terminal and prints to that, it won't be captured, but that is extremely rare. – Ted Lyngmo May 06 '20 at 08:55
Out of curiosity, how do you redirect only stderr in that shell? – Piotr Siupa May 06 '20 at 08:59
1

@NO_NAME That's a question that has been asked for eternety :-) One has to resort to sorcery. Here's one way: [Redirecting stderr in csh](https://stackoverflow.com/questions/32010883/redirecting-stderr-in-csh) I never use `csh` myself and this is one reason. – Ted Lyngmo May 06 '20 at 09:04

Redirect the output of g++ compiler to a file?

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