From: "Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>
To: mtk.manpages@gmail.com
Cc: libc-alpha@sourceware.org, linux-man@vger.kernel.org,
Ciprian Dorin Craciun <ciprian.craciun@gmail.com>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH v4] system.3: Document bug and workaround when the command name starts with a hypen
Date: Fri, 8 Jan 2021 15:28:42 +0100 [thread overview]
Message-ID: <a89dea2b-5b26-040a-2f12-3e096756f118@gmail.com> (raw)
In-Reply-To: <20210108142209.61938-1-alx.manpages@gmail.com>
On 1/8/21 3:22 PM, Alejandro Colomar wrote:
> man-pages bug: 211029
> https://bugzilla.kernel.org/show_bug.cgi?id=211029
>
> Complete workaround
Maybe a bit more readable:
Complete workaround example
> (it was too long for the page, but it may be useful here):
>
> ......
>
> $ sudo ln -s -T /usr/bin/echo /usr/bin/-echo;
> $ cc -o system_hyphen -x c - ;
> #include <stdlib.h>
>
> int
> main(void)
> {
> system(" -echo Hello world!");
> exit(EXIT_SUCCESS);
> }
>
> $ ./system_hyphen;
> Hello world!
>
> Reported-by: Ciprian Dorin Craciun <ciprian.craciun@gmail.com>
> Cc: Florian Weimer <fweimer@redhat.com>
> Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
> ---
>
> D'oh!
>
> man3/system.3 | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/man3/system.3 b/man3/system.3
> index 753d46f7d..ead35ab30 100644
> --- a/man3/system.3
> +++ b/man3/system.3
> @@ -255,6 +255,26 @@ 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)
> +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 to
> +.BR sh (1).)
> +To work around this problem,
> +prepend the command with a space as in the following call:
> +.PP
> +.RS 4
> +.EX
> + system(" \-unfortunate\-command\-name");
> +.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/
next prev parent reply other threads:[~2021-01-08 14:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 15:13 [RFC] system.3: Document bug when the command name starts with a hypen Alejandro Colomar
2021-01-04 15:54 ` Ciprian Dorin Craciun
2021-01-04 18:04 ` [PATCH] system.3: Document bug and workaround " Alejandro Colomar
2021-01-04 18:32 ` Alejandro Colomar (man-pages)
2021-01-04 20:02 ` Alejandro Colomar (man-pages)
2021-01-08 14:15 ` [PATCH v2] " Alejandro Colomar
2021-01-08 14:20 ` [PATCH v3] " Alejandro Colomar
2021-01-08 14:22 ` [PATCH v4] " Alejandro Colomar
2021-01-08 14:28 ` Alejandro Colomar (man-pages) [this message]
2021-01-18 15:28 ` Ping: " Alejandro Colomar (man-pages)
2021-01-18 15:37 ` Michael Kerrisk (man-pages)
2021-01-18 15:45 ` Alejandro Colomar (man-pages)
2021-01-18 15:58 ` Michael Kerrisk (man-pages)
2021-01-18 16:11 ` Alejandro Colomar (man-pages)
2021-01-18 15:36 ` Michael Kerrisk (man-pages)
2021-01-18 15:35 ` Michael Kerrisk (man-pages)
2021-01-05 13:23 ` [RFC] system.3: Document bug " Michael Kerrisk (man-pages)
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