From owner-freebsd-questions@FreeBSD.ORG Tue Feb 8 16:24:32 2005 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2F43016A4CE for ; Tue, 8 Feb 2005 16:24:32 +0000 (GMT) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id B886643D2F for ; Tue, 8 Feb 2005 16:24:31 +0000 (GMT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.13.1/8.13.1) id j18GOT88073139; Tue, 8 Feb 2005 10:24:29 -0600 (CST) (envelope-from dan) Date: Tue, 8 Feb 2005 10:24:29 -0600 From: Dan Nelson To: "Loren M. Lang" Message-ID: <20050208162429.GA82752@dan.emsphone.com> References: <20050208115928.GE8619@alzatex.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050208115928.GE8619@alzatex.com> X-OS: FreeBSD 5.3-STABLE X-message-flag: Outlook Error User-Agent: Mutt/1.5.6i cc: FreeBSD Mailing list Subject: Re: ktrace as a replacement for strace X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Feb 2005 16:24:32 -0000 In the last episode (Feb 08), Loren M. Lang said: > I'm looking for a replacement for the strace program I used to use on > linux; freebsd has a port of strace, but it just hangs everytime I > use it. It looks like the bsd version of strace would be > ktrace/kdump. I was able to get these to print a trace of the > program I ran, but it doesn't do all the nice substatuting that > strace was able to do. Mainly, I just want the first argument of open > to look like a string instead of a 32 bit pointer that I can't read. > I'm trying to figure out what files this program is trying to read so > I can edit it's configuration file. The string in the NAMI line immediately after an open() call is the filename in kdump output. strace actually does work, but I think it's losing a race when it forks the child process. Try suspending and resuming strace: (dan@dan.4) /home/dan> strace date ^Z zsh: 62219 suspended strace date [1] + suspended strace date (dan@dan.4) /home/dan> fg [1] + continued strace date execve(0xbfbfdef4, [0xbfbfe3b8], [/* 0 vars */]) = 0 mmap(0, 3920, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0) = 0x28071000 munmap(0x28071000, 3920) = 0 ... strace hasn't been updated in a while, though, and has problems parsing newer syscalls. Take a look at the truss command in the base system, which does about the same thing as strace. Ktrace has the advantage that it's less intrusive; both strace and truss have to stop the process to print out data, which really slow it down. -- Dan Nelson dnelson@allantgroup.com