bug#20796: [PATCH] Document behavior of sed -i -

[Stanislav Brabec]

"sed -i -" does not fail, but it also does not do what one would expect.
Document it, as it could have security implications:

Example:
The sed command below looks broken, but it is executed and succeeds:

ln -s /etc/passwd -- -
echo root | sed -i --follow-symlinks s/root/parrot/ -

Signed-off-by: Stanislav Brabec <address@hidden>
---
 doc/sed-in.texi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/sed-in.texi b/doc/sed-in.texi
index 0e10cde..c8f1289 100644
--- a/doc/sed-in.texi
+++ b/doc/sed-in.texi
@@ -180,6 +180,7 @@ sed OPTIONS... [SCRIPT] [INPUTFILE...]
 @end example
 
 If you do not specify @var{INPUTFILE}, or if @var{INPUTFILE} is @file{-},
+and @option{-i} is not used,
 @command{sed} filters the contents of the standard input.  The @var{script}
 is actually the first non-option parameter, which @command{sed} specially
 considers a script and not an input file if (and only if) none of the
-- 
2.4.2

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
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