cmd/pprof: -weblist and -output don't play well together #13413
Description
This issue isn't very serious but can be annoying nevertheless.
What version of Go are you using (go version)?
go 1.5.1 (the issue also exists in tip)
What operating system and processor architecture are you using?
not applicable
What did you do?
I was working on a headless system.
I wanted to analyse profiling output by running go tool pprof -weblist=. -output=listing.html myprogram myprogram.pprof and copying the resulting listing.html file to my workstation for viewing.
What did you expect to see?
I expected that there would be a file named listing.html containing the profiling report.
What did you see instead?
$ go tool pprof -weblist=. -output=listing.html myprogram myprogram.pprof
Generating report in listing.html
exec: "firefox": executable file not found in $PATH
The file listing.html was created, but remained empty.
Note that the same command works if I use -list instead of -weblist.
I think that the default behaviour of opening a browser to display the report is very convenient. But if the user specifies -output, that choice should either be respected or a warning (e.g. "warning : flag -output ignored for -weblist output format") should be printed. In no case an empty listing.html file should be generated.
As a workaround, I placed a small script named firefox in my $PATH; the script copies the report to a directory of my choice.