NAME

       fpathconf, pathconf - get configuration values for files

SYNOPSIS

       #include <unistd.h>

       long fpathconf(int fd, int name);
       long pathconf(const char *path, int name);

DESCRIPTION

       fpathconf() gets a value for the configuration option name for the open file descriptor fd.

       pathconf() gets a value for configuration option name for the filename path.

       The  corresponding  macros  defined  in  <unistd.h>  are  minimum values; if an application wants to take
       advantage of values which may change, a call to fpathconf() or pathconf() can be made,  which  may  yield
       more liberal results.

       Setting name equal to one of the following constants returns the following configuration options:

       _PC_LINK_MAX
              The  maximum  number  of  links  to  the file.  If fd or path refer to a directory, then the value
              applies to the whole directory.  The corresponding macro is _POSIX_LINK_MAX.

       _PC_MAX_CANON
              The maximum length of a formatted input line, where fd or path must  refer  to  a  terminal.   The
              corresponding macro is _POSIX_MAX_CANON.

       _PC_MAX_INPUT
              The maximum length of an input line, where fd or path must refer to a terminal.  The corresponding
              macro is _POSIX_MAX_INPUT.

       _PC_NAME_MAX
              The maximum length of a filename in the directory path or  fd  that  the  process  is  allowed  to
              create.  The corresponding macro is _POSIX_NAME_MAX.

       _PC_PATH_MAX
              The  maximum  length of a relative pathname when path or fd is the current working directory.  The
              corresponding macro is _POSIX_PATH_MAX.

       _PC_PIPE_BUF
              The maximum number of bytes that can be written atomically to a pipe of FIFO.  For fpathconf(), fd
              should  refer  to a pipe or FIFO.  For fpathconf(), path should refer to a FIFO or a directory; in
              the latter case, the  returned  value  corresponds  to  FIFOs  created  in  that  directory.   The
              corresponding macro is _POSIX_PIPE_BUF.

       _PC_CHOWN_RESTRICTED
              This  returns  a positive value if the use of chown(2) and fchown(2) for changing a file's user ID
              is restricted to a process with appropriate privileges, and changing a file's group ID to a  value
              other than the process's effective group ID or one of its supplementary group IDs is restricted to
              a process with appropriate privileges.  According  to  POSIX.1,  this  variable  shall  always  be
              defined with a value other than -1.  The corresponding macro is _POSIX_CHOWN_RESTRICTED.

              If fd or path refers to a directory, then the return value applies to all files in that directory.

       _PC_NO_TRUNC
              This  returns  nonzero if accessing filenames longer than _POSIX_NAME_MAX generates an error.  The
              corresponding macro is _POSIX_NO_TRUNC.

       _PC_VDISABLE
              This returns nonzero if special character processing can be disabled, where fd or path must  refer
              to a terminal.

RETURN VALUE

       The return value of these functions is one of the following:

       *  On  error,  -1  is  returned and errno is set to indicate the cause of the error (for example, EINVAL,
          indicating that name is invalid).

       *  If name corresponds to a maximum or minimum limit, and that limit is indeterminate, -1 is returned and
          errno  is not changed.  (To distinguish an indeterminate limit from an error, set errno to zero before
          the call, and then check whether errno is nonzero when -1 is returned.)

       *  If name corresponds to an option, a positive value is returned if the option is supported, and  -1  is
          returned if the option is not supported.

       *  Otherwise,  the  current  value  of  the  option  or  limit  is returned.  This value will not be more
          restrictive than the corresponding value that was  described  to  the  application  in  <unistd.h>  or
          <limits.h> when the application was compiled.

ERRORS

       EACCES (pathconf()) Search permission is denied for one of the directories in the path prefix of path.

       EBADF  (fpathconf()) fd is not a valid file descriptor.

       EINVAL name is invalid.

       EINVAL The implementation does not support an association of name with the specified file.

       ELOOP  (pathconf()) Too many symbolic links were encountered while resolving path.

       ENAMETOOLONG
              (pathconf()) path is too long.

       ENOENT (pathconf()) A component of path does not exist, or path is an empty string.

       ENOTDIR
              (pathconf()) A component used as a directory in path is not in fact a directory.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────┬───────────────┬─────────┐
       │Interface               │ Attribute     │ Value   │
       ├────────────────────────┼───────────────┼─────────┤
       │fpathconf(), pathconf() │ Thread safety │ MT-Safe │
       └────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008.

NOTES

       Files  with  name  lengths longer than the value returned for name equal to _PC_NAME_MAX may exist in the
       given directory.

       Some returned values may be huge; they are not suitable for allocating memory.

SEE ALSO

       getconf(1), open(2), statfs(2), confstr(3), sysconf(3)

COLOPHON

       This page is part of release 5.05 of  the  Linux  man-pages  project.   A  description  of  the  project,
       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       https://www.kernel.org/doc/man-pages/.