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[v3] system.3: Document bug and workaround when the command name starts with a hypen

Message ID 20210108142051.61875-1-alx.manpages@gmail.com
State New
Headers show
Series [v3] system.3: Document bug and workaround when the command name starts with a hypen | expand

Commit Message

Alejandro Colomar Jan. 8, 2021, 2:20 p.m. UTC 
man-pages bug: 211029
 https://bugzilla.kernel.org/show_bug.cgi?id=211029

Complete workaround
(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 - ;

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>
---

Hi Michael,

I forgot to remove some escapings in the commit message in v2.
I hope it arrives in time :)

Cheers,

Alex

 man3/system.3 | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
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Patch

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),