From: Junio C Hamano Date: Thu, 31 Aug 2006 21:31:22 GMT Subject: Re: [PATCH] Trace into open fd and refactor tracing code. Message-ID: <7vsljc8udx.fsf@assigned-by-dhcp.cox.net> In-Reply-To: Linus Torvalds writes: > That way, if you want to do the fd thing, you can always just do > > GIT_TRACE=/proc/self/fd/9 make test 9>/var/tmp/trace.log > > although I really don't know how well that works across a fork/exec that > may or may not be closing the file descriptor (I think it's much simpler > and more obvious to just give the filename directly). Actually it was me who suggested the use of fd directly, along with trying to do one message in a single write (i.e. not doing stdio as much as possible). Process A has fd=9 opened to /var/tmp/trace.log and forks process B. (1) process B execs something else, and just writes into fd=9 or (2) process B execs something else, perhaps after closing fd=9, and the exec'ed image opens /var/tmp/trace.log with "O_APPEND|O_CREAT" and gets a fd; it writes into this fd. I somehow felt there would be less interference between writes issued by process A and process B, but probably I am mistaken.