pathconf(3)

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
          returns  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
          returns  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
          returns  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
          returns  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
          returns  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
          returns  the  size  of the pipe buffer, where fd must refer to a
          pipe or FIFO and path must refer to a FIFO.   The  corresponding
          macro is _POSIX_PIPE_BUF.

   _PC_CHOWN_RESTRICTED
          returns  nonzero  if  the  chown(2) call may not be used on this
          file.  If fd or path refer to a directory, then this applies  to
          all  files  in  that  directory.   The  corresponding  macro  is
          _POSIX_CHOWN_RESTRICTED.

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

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

RETURN VALUE

   The  limit  is  returned, if one exists.  If the system does not have a
   limit for  the  requested  resource,  -1  is  returned,  and  errno  is
   unchanged.   If  there is an error, -1 is returned, and errno is set to
   reflect the nature of the error.

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 4.09 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/.

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