Using C++ with popen( "findscu -v" ) cannot get the output message in ubuntu18.04

Question

dcmtk3.6.3

I used C++ to code the function of popen("findscu -v", "r"). I want to get the output message of findscu to save in file. But it only print to the console, i cannot save to file.

//--verbose verbose mode, print processing details

FILE * fstream = popen("findscu --verbose", "r");
The output message of findscu is print to console.

char * p = fgets(buff, sizeof(buff), fstream);
p is NULL, and the buff is nothing.

But if i use this code:
//--help print this help text and exit
FILE * fstream = popen("findscu --help", "r");
It does not print to the console.

char * p = fgets(buff, sizeof(buff), fstream);
p is not NULL, and the buff has the output message.
That is what I want.

What is the differents of this two cases?
How to get the message from case 1?

thanks.

ubuntu18.04 C++ dcmtk3.6.3 findscu

//C++ dcmtk findscu
FILE * fstream = popen("findscu --verbose", "r");

char buff[10240] = {0};
char * p = fgets(buff, sizeof(buff), fstream);

cout <<  buff << endl;

I expect get output info from the buff, not from the console. Case 2 is what i want. Case 1 is what i dont want.

Possible duplicate of [c popen won't catch stderr](https://stackoverflow.com/questions/6900577/c-popen-wont-catch-stderr) — Davis Herring, May 24 '19 at 03:51
Why don't you specify an appropriate logger configuration file with findscu's --log-config option? This would allow you to direct all output immediately to a file. Also in case you are only interested in the C-FIND response datasets, you should try one of the --extract options. — J. Riesmeier, May 24 '19 at 16:01
`findscu` outputs to `stderr` but you are trying to capture `stdout` — albeksdurf, Jul 31 '20 at 07:38

Using C++ with popen( "findscu -v" ) cannot get the output message in ubuntu18.04

0 Answers0