Re: Problem in bin/sh stripping the * character through ${expansion%}
Doug, good day.
Thu, Aug 06, 2009 at 11:15:12AM -0700, Doug Barton wrote:
> I came across this problem during a recent portmaster update. When
> trying to strip off the * character using variable expansion in bin/sh
> it doesn't work. Other "special" characters do work if they are
> properly escaped.
>
> The attached mini-script clearly shows the problem:
>
> $ sh sh-strip-problem
> var before stripping: foo\*
> var after stripping: foo\*
>
> var before stripping: foo\$
> var after stripping: foo\
According to the sh(1), it is not a problem. Namely,
- \* being unquoted at all will produce a lone '*';
- '*' when treated as the smallest pattern, will result in a stripping
of a zero-length string -- it is the smallest pattern in the case of
'*' that matches anything.
In order to strip the trailing star you should use
-
var=${var%[*]}
-
This gives you the pattern of '[*]' that is properly treated as the
single star -- it's a weird way to escape the star in the patterns.
Other characters work, but only because they produce no patterns.
In principle, you can try \? that will remove any trailing character
no matter what, since it is the second character that will produce
the pattern.
> In contrast, bash does the right thing:
>
> bash sh-strip-problem
> var before stripping: foo\*
> var after stripping: foo\
>
> var before stripping: foo\$
> var after stripping: foo\
I will try to look at the XCU to understand what is the POSIX
way of doing the things.
--
Eygene
____ _.--. #
\`.|\.....-'` `-._.-'_.-'` # Remember that it is hard
/ ' ` , __.--' # to read the on-line manual
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{_.-``-' {_/#
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Re: Problem in bin/sh stripping the * character through ${expansion%}
Johan van Selst wrote:
> When I tried it myself, I automatically typed quotes, which does work
> var="${var%\*}"
Really should learn to read better: this in fact procudes 'foo'
rather than 'foo\' in the given example case. Again, not like bash.
Johan
pgpbI94sMye6i.pgp
Description: PGP signature
Re: Problem in bin/sh stripping the * character through ${expansion%}
Doug Barton wrote:
> I came across this problem during a recent portmaster update. When
> trying to strip off the * character using variable expansion in bin/sh
> it doesn't work. Other "special" characters do work if they are
> properly escaped.
Your script does
var=${var%\*}
When I tried it myself, I automatically typed quotes, which does work
var="${var%\*}"
Alternatively you could use (with or without quotes)
var="${var%[*]}"
Still, I don't see a reason why your variant shouldn't work as well..
Regards,
Johan
pgpF040hK1k5O.pgp
Description: PGP signature
Problem in bin/sh stripping the * character through ${expansion%}
Howdy,
I came across this problem during a recent portmaster update. When
trying to strip off the * character using variable expansion in bin/sh
it doesn't work. Other "special" characters do work if they are
properly escaped.
The attached mini-script clearly shows the problem:
$ sh sh-strip-problem
var before stripping: foo\*
var after stripping: foo\*
var before stripping: foo\$
var after stripping: foo\
In contrast, bash does the right thing:
bash sh-strip-problem
var before stripping: foo\*
var after stripping: foo\
var before stripping: foo\$
var after stripping: foo\
Should I go ahead and file a PR on this?
Doug
--
This .signature sanitized for your protection
var='foo\*'
echo "var before stripping: $var"
var=${var%\*}
echo "var after stripping: $var"
echo ''
var='foo\$'
echo "var before stripping: $var"
var=${var%\$}
echo "var after stripping: $var"
exit 0
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Re: sosend() and mbuf
On Tuesday 04 August 2009 12:57:25 pm Dag-Erling Smørgrav wrote: > Ed Schouten writes: > > Maslan writes: > > > However, when i checked the pid & tid of the new created thread it > > > was not the same as the parent nor as the proc0 & thread0 > > I am not sure, but sharing another process's address space doesn't have > > to imply it shares the same pid, right? > > The man page explicitly states that if no process is specified, the new > thread is assigned to proc0, which has a valid filedesc table, valid > creds etc., so this shouldn't be a problem. However, he's getting a > different PID, which shouldn't happen. Either the man page is wrong, or > things were different in 7. proc0 does not have a fully valid file descriptor table. It has a structure, but fd_[cjr]dir are not initialized to point at anything. File descriptors are a property of userland processes, not of kernel processes. However, fd_[cjr]dir need to be valid to perform any namei() lookup even if one is simply going to do a vn_open() on the resulting vnode (which is more approprate for kernel code to do, if it is to open a file at all). -- John Baldwin ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
