.\" Copyright (c) 1993 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.roff%
.\"
.\"	@(#)pathconf.2	5.1 (Berkeley) 05/24/93
.\"
.Dd 
.Dt PATHCONF 2
.Os BSD 4
.Sh NAME
.Nm pathconf ,
.Nm fpathconf
.Nd get configurable pathname variables
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft long
.Fn pathconf "const char *path" "int name"
.Ft long
.Fn fpathconf "int fd" "int name"
.Sh DESCRIPTION
.Bf -symbolic
This interface is obsoleted by sysctl(3).
.Ef
.Pp
The
.Fn pathconf
and
.Fn fpathconf
functions provides a method for applications to determine the current
value of a configurable system limit or option variable associated
with a pathname or file descriptor.
.Pp
For
.Nm pathconf ,
the
.Fa path
argument is the name of a file or directory.
For
.Nm fpathconf ,
the
.Fa fd
argument is an open file descriptor.
The
.Fa name
argument specifies the system variable to be queried.
Symbolic constants for each name value are found in the include file
.Li <unistd.h> .
.Pp
The available values are as follows:
.Pp
.Bl -tag -width "123456"
.Pp
.It Li _PC_LINK_MAX
The maximum file link count.
.It Li _PC_MAX_CANON
The maximum number of bytes in terminal canonical input line.
.It Li _PC_MAX_INPUT
The minimum maximum number of bytes for which space is available in
a terminal input queue.
.It Li _PC_NAME_MAX
The maximum number of bytes in a file name.
.It Li _PC_PATH_MAX
The maximum number of bytes in a pathname.
.It Li _PC_PIPE_BUF
The maximum number of bytes which will be written atomically to a pipe.
.It Li _PC_CHOWN_RESTRICTED
Return 1 if appropriate privileges are required for the
.Xr chown 2
system call, otherwise 0.
.It Li _PC_NO_TRUNC
Return 1 if file names longer than KERN_NAME_MAX are truncated.
.It Li _PC_VDISABLE
Returns the terminal character disabling value.
.El
.Sh RETURN VALUES
If the call to
.Nm pathconf
or
.Nm fpathconf
is not successful, \-1 is returned and
.Va errno
is set appropriately.
Otherwise, if the variable is associated with functionality that does
not have a limit in the system, \-1 is returned and
.Va errno
is not modified.
Otherwise, the current variable value is returned.
.Sh ERRORS
The
.Nm pathconf
function may fail and set
.Va error
for any of the errors specified for the library functions
.Xr lstat 2
or
.Xr sysctl 3 .
.Pp
The
.Nm fpathconf
function may fail and set
.Va error
for any of the errors specified for the library functions
.Xr lseek 2
or
.Xr sysctl 3 .
.Pp
In addition, the following errors may be reported:
.Bl -tag -width Er
.It Bq Er EINVAL
The value of the
.Fa name
argument is invalid.
.Sh SEE ALSO
.Xr sysctl 3
.Sh HISTORY
The
.Nm pathconf
and
.Nm fpathconf
functions first appeared in 4.4BSD.