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Mon, 04 Jan 2021 12:02:04 -0800 (PST) Subject: Re: [PATCH] system.3: Document bug and workaround when the command name starts with a hypen From: "Alejandro Colomar (man-pages)" To: mtk.manpages@gmail.com Cc: libc-alpha@sourceware.org, linux-man@vger.kernel.org, Ciprian Dorin Craciun , Florian Weimer References: <20210104180420.74092-1-alx.manpages@gmail.com> <5c64d9f9-5bef-ba6a-ac7c-b119ce61d731@gmail.com> Message-ID: <0d69b38d-2dc0-31ca-1218-c5483bf507b7@gmail.com> Date: Mon, 4 Jan 2021 21:02:03 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:84.0) Gecko/20100101 Thunderbird/84.0 MIME-Version: 1.0 In-Reply-To: <5c64d9f9-5bef-ba6a-ac7c-b119ce61d731@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org D'oh On 1/4/21 7:32 PM, Alejandro Colomar (man-pages) wrote: > Hi Michael, > > See a few corrections below. > > Cheers, > > Alex > > On 1/4/21 7:04 PM, Alejandro Colomar wrote: >> man-pages bug: 211029 >> https://bugzilla.kernel.org/show_bug.cgi?id=211029 >> >> Reported-by: Ciprian Dorin Craciun >> Cc: Florian Weimer >> Signed-off-by: Alejandro Colomar >> --- >> man3/system.3 | 34 ++++++++++++++++++++++++++++++++++ >> 1 file changed, 34 insertions(+) >> >> diff --git a/man3/system.3 b/man3/system.3 >> index aef40417a..0310d9a04 100644 >> --- a/man3/system.3 >> +++ b/man3/system.3 >> @@ -250,6 +250,40 @@ are not executed. >> Such risks are especially grave when using >> .BR system () >> from a privileged program. >> +.SH BUGS >> +./" [BUG 211029](https://bugzilla.kernel.org/show_bug.cgi?id=211029) >> +./" [Glibc bug](https://sourceware.org/bugzilla/show_bug.cgi?id=27143) >> +./" [POSIX bug](https://www.austingroupbugs.net/view.php?id=1440) s%/%\\% >> +If the command name starts with a hyphen, >> +.BR sh (1) >> +interprets the command name as an option, >> +and the behavior is undefined >> +(See the >> +.B \-c >> +option in > > option to > >> +.BR sh (1).). >> +To work around this problem, >> +prepend the command with a space as below: >> +.PP >> +.RS 4 >> +.EX >> +/* system_hyphen.c */ >> + >> +#include >> + >> +int >> +main(void) >> +{ >> + system(" -echo Hello world!"); > > \-echo > >> + exit(EXIT_SUCCESS); >> +} >> +.PP >> +.RB "$" " sudo ln \-s \-T /usr/bin/echo /usr/bin/\-echo;" >> +.RB "$" " cc \-o system_hyphen system_hyphen.c;" >> +.RB "$" " ./system_hyphen;" >> +Hello world! >> +.EE >> +.RE >> .SH SEE ALSO >> .BR sh (1), >> .BR execve (2), >> > -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/