X-Recipient: archive-cygwin@delorie.com X-SWARE-Spam-Status: No, hits=-1.6 required=5.0 tests=AWL,BAYES_00,KHOP_THREADED,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org From: Adam Dinwoodie To: "cygwin@cygwin.com" Subject: RE: Shell script loop runs out of memory Date: Fri, 1 Jun 2012 10:06:14 +0000 Deferred-Delivery: Fri, 1 Jun 2012 10:06:00 +0000 Message-ID: References: <786EBDA1AC46254B813E200779E7AD36023A42C2@srv1163ex1.flightsafety.com> <0105D5C1E0353146B1B222348B0411A20A770C827D@NIHMLBX02.nih.gov> In-Reply-To: Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 X-IsSubscribed: yes Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by delorie.com id q51A9HLM012207 AZ 9901 wrote: > So some things to avoid while (bash)scripting under Cygwin to limit > BLODA effect : > - | : pipe stdout --> stdin > - $(...) : subshell fork > - `...` : same as before, subshell fork > - [ condition ] : prefer [[ condition ]] construction > - anything else ? By my understanding of the discussion, any sort of forking, ie anything that will require the bash interpreter to make a system() call. In particular, including pipes in the above is somewhat of a red herring, since it's not the pipe that's the problem, but the commands either side of it. Calling any sort of executable (script, binary, whatever) will cause a fork. Anything that requires a subshell (in bash, that's the subshell forks, the ( ... ) command syntax, etc), will similarly require a fork. Shell builtins (eg echo) almost certainly won't require a fork. Note that not everything you might expect to be a builtin is, however: bash doesn't have a "sleep" builtin, for example. You can check whether something's a builtin by calling "type command" from the bash shell.