On 08/01/2013 12:11 AM, Eric Blake wrote: > Indeed, I think you have a real bug after all - xargs should not be > prompting for the fourth command until after it reaps the echo process > spawned by the affirmative answer to the third prompt.
The fix seems to be quite easy (i.e. I didn't see any side effects). Have a nice day, Berny >From 92c6596d151c93797d559036b4af879c1c320259 Mon Sep 17 00:00:00 2001 From: Bernhard Voelker <m...@bernhard-voelker.de> Date: Fri, 2 Aug 2013 14:16:27 +0200 Subject: [PATCH] xargs: wait for process before prompting in interactive mode (-p) In interactive mode, there is a race between xargs prompting about the next command to be run, vs. the execution of the echo command: $ echo 1 2 | xargs -n 1 -p /bin/echo 1 ?...y /bin/echo 2 ?...1 y 2 This behavior violates POSIX: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/xargs.html): The xargs utility shall then invoke the constructed command line and wait for its completion. This sequence shall be repeated until one of the following occurs: [...] * xargs/xargs.c (xargs_do_exec): Move the code for waiting for forked processes up, so that the process terminated before prompting for the next command. * NEWS: Mention the fix. Reported by jida...@jidanni.org in http://lists.gnu.org/archive/html/bug-findutils/2013-07/msg00015.html --- NEWS | 2 ++ xargs/xargs.c | 15 ++++++++------- 2 files changed, 10 insertions(+), 7 deletions(-) diff --git a/NEWS b/NEWS index 4349a21..e0a41a3 100644 --- a/NEWS +++ b/NEWS @@ -34,6 +34,8 @@ database, though they are in the ChangeLog: *** Don't delete header files in "lib/" for "make clean". +*** xargs: wait for process before prompting in interactive mode (-p) + These following fixed bugs are recorded at https://savannah.gnu.org/bugs/?group=findutils: diff --git a/xargs/xargs.c b/xargs/xargs.c index e0b2421..35c1198 100644 --- a/xargs/xargs.c +++ b/xargs/xargs.c @@ -1179,15 +1179,16 @@ xargs_do_exec (struct buildcmd_control *ctl, void *usercontext, int argc, char * (void) argc; (void) usercontext; + if (proc_max) + { + while (procs_executing >= proc_max) + { + wait_for_proc (false, 1u); + } + } + if (!query_before_executing || print_args (true)) { - if (proc_max) - { - while (procs_executing >= proc_max) - { - wait_for_proc (false, 1u); - } - } if (!query_before_executing && print_command) print_args (false); -- 1.8.3.1
