Except the system call version doesn't need you to include any header files! Which is NOT clear from the man page!
> On 13 Feb 2020, at 13:53, George N. White III <gnw...@gmail.com> wrote: > > >> On Thu, 13 Feb 2020 at 06:40, Andy Paterson via users >> <users@lists.fedoraproject.org> wrote: > >> [...] >> I am a little confused by getcwd(), on linux it is supposed to be a system >> call .. I expect to find a manual page for it in section 2 (man 2 getcwd) >> instead it gives me the library function manual page from section 3 (man 3 >> getcwd) > > $ man -k getcwd > getcwd (2) - get current working directory > getcwd (3) - get current working directory > getcwd (3p) - get the pathname of the current working directory > $ gzip -dc /usr/share/man/man2/getcwd.2.gz > .so man3/getcwd.3 > >> I would fully expect a libc version of getcwd to make many system calls to >> traverse the current path but here getcwd() is a system call with all work >> done internally in the kernel, so I wouldnt expect anything to probe the >> path elements. >> When I knock up a simple program to do a getcwd() and strace it I find that >> getcwd (on FC31 anyway) IS a system call. >> Why does "man getcwd" give me a page from section 3? > > The man page explains the differences, so it makes sense that "man 2" and > "man 3" give the same text: > > C library/kernel differences > On Linux, the kernel provides a getcwd() system call, which the func‐ > tions described in this page will use if possible. The system call > takes the same arguments as the library function of the same name, but > is limited to returning at most PATH_MAX bytes. > > The getcwd() system call saves overhead but should make the same storage > accesses as the > library version. > > -- > George N. White III > > _______________________________________________ > users mailing list -- users@lists.fedoraproject.org > To unsubscribe send an email to users-le...@lists.fedoraproject.org > Fedora Code of Conduct: > https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: > https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org
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