Re: extra slash in current path

From: Nick Bowler
Date: Thu Jun 23 2011 - 10:27:19 EST

On 2011-06-23 10:11 -0400, yuyichao-mit wrote:
> On Thu, Jun 23, 2011 at 9:54 AM, richard -rw- weinberger
> > Is this really a kernel issue?
> > rw@raccoon:~> cd //
> > rw@raccoon://> pwd
> > //
> > rw@raccoon://> ls -l /proc/self/cwd
> > lrwxrwxrwx 1 rw users 0 23. Jun 15:53 /proc/self/cwd -> /
> well, that's true, but this is indeed the retrun value of get_current_dir_name.

glibc's get_current_dir_name will honour the PWD environment variable in some
cases, which is where the // actually comes from (i.e., it does not come
from the kernel).

This funny behaviour of cd is actually specified by POSIX (man 1p cd):

8. The curpath value shall then be converted to canonical form
as follows, considering each component from beginning to
end, in sequence:
c. An implementation may further simplify curpath by
removing any trailing slash characters that are not also
leading slashes, replacing multiple non-leading
consecutive slashes with a single slash, and replacing
three or more leading slashes with a single slash. If,
as a result of this canonicalization, the curpath
variable is null, no further steps shall be taken.

9. [...] The PWD environment variable shall be set to curpath.

Nick Bowler, Elliptic Technologies (
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