* extra slash in current path @ 2011-06-23 13:14 yuyichao-mit 2011-06-23 13:17 ` Alessandro Suardi 2011-06-23 13:31 ` Lars Täuber 0 siblings, 2 replies; 14+ messages in thread From: yuyichao-mit @ 2011-06-23 13:14 UTC (permalink / raw) To: linux-kernel, linux-c-programming The problem is like this: $ cd / $ pwd / $ cd / $ pwd // $ cd /// $ pwd / Why can there be a extra slash (and exactly one) in current path? Is this designed on purpose? This is not really a big deal but I think it can confuse some program. Thanks. Yichao ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 13:14 extra slash in current path yuyichao-mit @ 2011-06-23 13:17 ` Alessandro Suardi [not found] ` <BANLkTik3iMqZJiEY1+DYS2T9=+q2x2=5pQ@mail.gmail.com> 2011-06-23 13:31 ` Lars Täuber 1 sibling, 1 reply; 14+ messages in thread From: Alessandro Suardi @ 2011-06-23 13:17 UTC (permalink / raw) To: yuyichao-mit; +Cc: linux-kernel, linux-c-programming On Thu, Jun 23, 2011 at 3:14 PM, yuyichao-mit <yuyichao@mit.edu> wrote: > The problem is like this: > > $ cd / > $ pwd > / > > $ cd / > $ pwd > // > > $ cd /// > $ pwd > / > > Why can there be a extra slash (and exactly one) in current path? Is > this designed on purpose? > This is not really a big deal but I think it can confuse some program. Multiple consecutive slashes should not confuse any program. http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap03.html#tag_03_266 --alessandro "There's always a siren singing you to shipwreck" (Radiohead, "There There") ^ permalink raw reply [flat|nested] 14+ messages in thread
[parent not found: <BANLkTik3iMqZJiEY1+DYS2T9=+q2x2=5pQ@mail.gmail.com>]
* Re: extra slash in current path [not found] ` <BANLkTik3iMqZJiEY1+DYS2T9=+q2x2=5pQ@mail.gmail.com> @ 2011-06-23 13:26 ` yuyichao-mit 0 siblings, 0 replies; 14+ messages in thread From: yuyichao-mit @ 2011-06-23 13:26 UTC (permalink / raw) To: linux-c-programming, linux-kernel Well, actually, I mean why is // so special if more than two slash at the beginning of absolute path become only one slash? Yichao Yu On Thu, Jun 23, 2011 at 9:17 AM, Alessandro Suardi <alessandro.suardi@gmail.com> wrote: > On Thu, Jun 23, 2011 at 3:14 PM, yuyichao-mit <yuyichao@mit.edu> wrote: >> The problem is like this: >> >> $ cd / >> $ pwd >> / >> >> $ cd / >> $ pwd >> // >> >> $ cd /// >> $ pwd >> / >> >> Why can there be a extra slash (and exactly one) in current path? Is >> this designed on purpose? >> This is not really a big deal but I think it can confuse some program. > > Multiple consecutive slashes should not confuse any program. > > http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap03.html#tag_03_266 > > --alessandro > > "There's always a siren singing you to shipwreck" > > (Radiohead, "There There") > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 13:14 extra slash in current path yuyichao-mit 2011-06-23 13:17 ` Alessandro Suardi @ 2011-06-23 13:31 ` Lars Täuber 2011-06-23 13:32 ` yuyichao-mit 1 sibling, 1 reply; 14+ messages in thread From: Lars Täuber @ 2011-06-23 13:31 UTC (permalink / raw) To: yuyichao-mit; +Cc: linux-kernel Hi, Am Thu, 23 Jun 2011 09:14:18 -0400 yuyichao-mit <yuyichao@mit.edu> schrieb: > The problem is like this: > > $ cd / > $ pwd > / > > $ cd / > $ pwd > // didn't you mean?: $ cd // $ pwd // Regards Lars > > $ cd /// > $ pwd > / > > Why can there be a extra slash (and exactly one) in current path? Is > this designed on purpose? > This is not really a big deal but I think it can confuse some program. > > Thanks. > > Yichao ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 13:31 ` Lars Täuber @ 2011-06-23 13:32 ` yuyichao-mit 2011-06-23 13:54 ` richard -rw- weinberger 0 siblings, 1 reply; 14+ messages in thread From: yuyichao-mit @ 2011-06-23 13:32 UTC (permalink / raw) To: Lars Täuber; +Cc: linux-kernel On Thu, Jun 23, 2011 at 9:31 AM, Lars Täuber <taeuber@bbaw.de> wrote: > Hi, > > Am Thu, 23 Jun 2011 09:14:18 -0400 > yuyichao-mit <yuyichao@mit.edu> schrieb: >> The problem is like this: >> >> $ cd / >> $ pwd >> / >> >> $ cd / >> $ pwd >> // > > didn't you mean?: > $ cd // > $ pwd > // yes, exactly. Sorry for the typo (copy-paste~~~) > > > Regards > Lars > >> >> $ cd /// >> $ pwd >> / >> >> Why can there be a extra slash (and exactly one) in current path? Is >> this designed on purpose? >> This is not really a big deal but I think it can confuse some program. >> >> Thanks. >> >> Yichao > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 13:32 ` yuyichao-mit @ 2011-06-23 13:54 ` richard -rw- weinberger 2011-06-23 14:11 ` yuyichao-mit 0 siblings, 1 reply; 14+ messages in thread From: richard -rw- weinberger @ 2011-06-23 13:54 UTC (permalink / raw) To: yuyichao-mit; +Cc: Lars Täuber, linux-kernel On Thu, Jun 23, 2011 at 3:32 PM, yuyichao-mit <yuyichao@mit.edu> wrote: > On Thu, Jun 23, 2011 at 9:31 AM, Lars Täuber <taeuber@bbaw.de> wrote: >> Hi, >> >> Am Thu, 23 Jun 2011 09:14:18 -0400 >> yuyichao-mit <yuyichao@mit.edu> schrieb: >>> The problem is like this: >>> >>> $ cd / >>> $ pwd >>> / >>> >>> $ cd / >>> $ pwd >>> // >> >> didn't you mean?: >> $ cd // >> $ pwd >> // > > yes, exactly. > > Sorry for the typo (copy-paste~~~) > 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 -> / -- Thanks, //richard ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 13:54 ` richard -rw- weinberger @ 2011-06-23 14:11 ` yuyichao-mit 2011-06-23 14:25 ` richard -rw- weinberger ` (2 more replies) 0 siblings, 3 replies; 14+ messages in thread From: yuyichao-mit @ 2011-06-23 14:11 UTC (permalink / raw) To: richard -rw- weinberger Cc: Lars Täuber, linux-kernel, linux-c-programming On Thu, Jun 23, 2011 at 9:54 AM, richard -rw- weinberger <richard.weinberger@gmail.com> wrote: > On Thu, Jun 23, 2011 at 3:32 PM, yuyichao-mit <yuyichao@mit.edu> wrote: >> On Thu, Jun 23, 2011 at 9:31 AM, Lars Täuber <taeuber@bbaw.de> wrote: >>> Hi, >>> >>> Am Thu, 23 Jun 2011 09:14:18 -0400 >>> yuyichao-mit <yuyichao@mit.edu> schrieb: >>>> The problem is like this: >>>> >>>> $ cd / >>>> $ pwd >>>> / >>>> >>>> $ cd / >>>> $ pwd >>>> // >>> >>> didn't you mean?: >>> $ cd // >>> $ pwd >>> // >> >> yes, exactly. >> >> Sorry for the typo (copy-paste~~~) >> > > 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. #include <unistd.h> #include <stdio.h> int main() { char *cwd = get_current_dir_name(); printf("%s\n", cwd); return 0; } $ cd // $ pwd // $ main // so is this a glibc stuff?? (that's y I also send to linux-c-programming.) > > -- > Thanks, > //richard > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 14:11 ` yuyichao-mit @ 2011-06-23 14:25 ` richard -rw- weinberger 2011-06-23 14:27 ` Nick Bowler 2011-06-23 14:31 ` Michael Tokarev 2 siblings, 0 replies; 14+ messages in thread From: richard -rw- weinberger @ 2011-06-23 14:25 UTC (permalink / raw) To: yuyichao-mit; +Cc: Lars Täuber, linux-kernel, linux-c-programming On Thu, Jun 23, 2011 at 4:11 PM, yuyichao-mit <yuyichao@mit.edu> wrote: > On Thu, Jun 23, 2011 at 9:54 AM, richard -rw- weinberger > <richard.weinberger@gmail.com> wrote: >> On Thu, Jun 23, 2011 at 3:32 PM, yuyichao-mit <yuyichao@mit.edu> wrote: >>> On Thu, Jun 23, 2011 at 9:31 AM, Lars Täuber <taeuber@bbaw.de> wrote: >>>> Hi, >>>> >>>> Am Thu, 23 Jun 2011 09:14:18 -0400 >>>> yuyichao-mit <yuyichao@mit.edu> schrieb: >>>>> The problem is like this: >>>>> >>>>> $ cd / >>>>> $ pwd >>>>> / >>>>> >>>>> $ cd / >>>>> $ pwd >>>>> // >>>> >>>> didn't you mean?: >>>> $ cd // >>>> $ pwd >>>> // >>> >>> yes, exactly. >>> >>> Sorry for the typo (copy-paste~~~) >>> >> >> 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. > > #include <unistd.h> > #include <stdio.h> > > int main() > { > char *cwd = get_current_dir_name(); > printf("%s\n", cwd); > return 0; > } > > $ cd // > $ pwd > // > $ main > // > > so is this a glibc stuff?? I guess glibc does some caching. > (that's y I also send to linux-c-programming.) Ah, ok. -- Thanks, //richard ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 14:11 ` yuyichao-mit 2011-06-23 14:25 ` richard -rw- weinberger @ 2011-06-23 14:27 ` Nick Bowler 2011-06-23 14:31 ` Michael Tokarev 2 siblings, 0 replies; 14+ messages in thread From: Nick Bowler @ 2011-06-23 14:27 UTC (permalink / raw) To: yuyichao-mit Cc: richard -rw- weinberger, Lars Täuber, linux-kernel, linux-c-programming 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. Cheers, -- Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/) ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 14:11 ` yuyichao-mit 2011-06-23 14:25 ` richard -rw- weinberger 2011-06-23 14:27 ` Nick Bowler @ 2011-06-23 14:31 ` Michael Tokarev 2011-06-23 14:52 ` Lars Täuber 2011-06-23 14:53 ` yuyichao-mit 2 siblings, 2 replies; 14+ messages in thread From: Michael Tokarev @ 2011-06-23 14:31 UTC (permalink / raw) To: yuyichao-mit Cc: richard -rw- weinberger, Lars Täuber, linux-kernel, linux-c-programming 23.06.2011 18:11, yuyichao-mit wrote: >>>> $ cd // >>>> $ pwd >>>> // The current directory is cached in $PWD environment variable by shell (bash at least). This variable is checked in glibc (getcwd() et al) - if it is set and stat($PWD) is the same as stat("."), that value is used. It has nothing to do with kernel, probably the issue is in bash which somehow allows double slash for root dir (but not triple). /mjt ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 14:31 ` Michael Tokarev @ 2011-06-23 14:52 ` Lars Täuber [not found] ` <BANLkTimdzyT6w2LoKtTjhHTKF5d6zWXFGw@mail.gmail.com> 2011-06-23 14:53 ` yuyichao-mit 1 sibling, 1 reply; 14+ messages in thread From: Lars Täuber @ 2011-06-23 14:52 UTC (permalink / raw) To: linux-kernel Am Thu, 23 Jun 2011 18:31:06 +0400 Michael Tokarev <mjt@tls.msk.ru> schrieb: > 23.06.2011 18:11, yuyichao-mit wrote: > > >>>> $ cd // > >>>> $ pwd > >>>> // > > The current directory is cached in $PWD environment > variable by shell (bash at least). This variable is > checked in glibc (getcwd() et al) - if it is set and > stat($PWD) is the same as stat("."), that value is used. It also is somehow cached inside bash/dash for it's built in commands. $ cd // $ export PWD=5 $ pwd // $ /bin/pwd / Regards Lars ^ permalink raw reply [flat|nested] 14+ messages in thread
[parent not found: <BANLkTimdzyT6w2LoKtTjhHTKF5d6zWXFGw@mail.gmail.com>]
* Re: extra slash in current path [not found] ` <BANLkTimdzyT6w2LoKtTjhHTKF5d6zWXFGw@mail.gmail.com> @ 2011-06-23 15:02 ` 俞颐超 0 siblings, 0 replies; 14+ messages in thread From: 俞颐超 @ 2011-06-23 15:02 UTC (permalink / raw) To: linux-kernel, linux-c-programming On Thu, Jun 23, 2011 at 10:52 AM, Lars Täuber <taeuber@bbaw.de> wrote: > Am Thu, 23 Jun 2011 18:31:06 +0400 > Michael Tokarev <mjt@tls.msk.ru> schrieb: >> 23.06.2011 18:11, yuyichao-mit wrote: >> >> >>>> $ cd // >> >>>> $ pwd >> >>>> // >> >> The current directory is cached in $PWD environment >> variable by shell (bash at least). This variable is >> checked in glibc (getcwd() et al) - if it is set and >> stat($PWD) is the same as stat("."), that value is used. > > It also is somehow cached inside bash/dash for it's built in commands. > $ cd // > $ export PWD=5 this PWD=5 is not necessary. > $ pwd > // > $ /bin/pwd > / $ export PWD=//// $ /bin/pwd / $ pwd // $ echo $PWD //// $ a.out (simply output get_current_dir_name()) //// so getcwd indeed use $PWD (for symlink?) but pwd and /bin/pwd both simplify the output although bash simplify it in a strange way~~~ ~~interesting > > > Regards > Lars > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path 2011-06-23 14:31 ` Michael Tokarev @ 2011-06-23 14:53 ` yuyichao-mit 2011-06-23 14:53 ` yuyichao-mit 1 sibling, 0 replies; 14+ messages in thread From: yuyichao-mit @ 2011-06-23 14:53 UTC (permalink / raw) To: Michael Tokarev Cc: richard -rw- weinberger, Lars Täuber, linux-kernel, linux-c-programming On Thu, Jun 23, 2011 at 10:31 AM, Michael Tokarev <mjt@tls.msk.ru> wrote: > 23.06.2011 18:11, yuyichao-mit wrote: > >>>>> $ cd // >>>>> $ pwd >>>>> // > > The current directory is cached in $PWD environment > variable by shell (bash at least). This variable is > checked in glibc (getcwd() et al) - if it is set and > stat($PWD) is the same as stat("."), that value is used. > > It has nothing to do with kernel, probably the issue > is in bash which somehow allows double slash for root > dir (but not triple). u r right. chdir in c and cd in csh doesn't have this problem. it is bash stuff. > > /mjt > -- To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: extra slash in current path @ 2011-06-23 14:53 ` yuyichao-mit 0 siblings, 0 replies; 14+ messages in thread From: yuyichao-mit @ 2011-06-23 14:53 UTC (permalink / raw) To: Michael Tokarev Cc: richard -rw- weinberger, Lars Täuber, linux-kernel, linux-c-programming On Thu, Jun 23, 2011 at 10:31 AM, Michael Tokarev <mjt@tls.msk.ru> wrote: > 23.06.2011 18:11, yuyichao-mit wrote: > >>>>> $ cd // >>>>> $ pwd >>>>> // > > The current directory is cached in $PWD environment > variable by shell (bash at least). This variable is > checked in glibc (getcwd() et al) - if it is set and > stat($PWD) is the same as stat("."), that value is used. > > It has nothing to do with kernel, probably the issue > is in bash which somehow allows double slash for root > dir (but not triple). u r right. chdir in c and cd in csh doesn't have this problem. it is bash stuff. > > /mjt > ^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2011-06-23 15:02 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-06-23 13:14 extra slash in current path yuyichao-mit
2011-06-23 13:17 ` Alessandro Suardi
[not found] ` <BANLkTik3iMqZJiEY1+DYS2T9=+q2x2=5pQ@mail.gmail.com>
2011-06-23 13:26 ` yuyichao-mit
2011-06-23 13:31 ` Lars Täuber
2011-06-23 13:32 ` yuyichao-mit
2011-06-23 13:54 ` richard -rw- weinberger
2011-06-23 14:11 ` yuyichao-mit
2011-06-23 14:25 ` richard -rw- weinberger
2011-06-23 14:27 ` Nick Bowler
2011-06-23 14:31 ` Michael Tokarev
2011-06-23 14:52 ` Lars Täuber
[not found] ` <BANLkTimdzyT6w2LoKtTjhHTKF5d6zWXFGw@mail.gmail.com>
2011-06-23 15:02 ` 俞颐超
2011-06-23 14:53 ` yuyichao-mit
2011-06-23 14:53 ` yuyichao-mit
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.