ln.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)ln.1	8.1	9/11/90
.TH ln 1
.SH Name
ln \- link to a file
.SH Syntax
.B ln
[ \fB\-f\fR ] [ \fB\-i\fR ] [ \fB\-s\fR ] \fIname1\fR [\|\fIname2\fR\|]
.br
.B ln
[ \fB\-f\fR ] [ \fB\-i\fR ] [ \fB\-s\fR ] name ... directory
.SH Description
.NXR "ln command"
.NXR "link" "creating"
.NXAM "ln command" "lstat system call"
.NXAM "ln command" "readlink system call"
.NXAM "ln command" "symlink system call"
.NXAM "ln command" "link system call"
A link is a directory entry referring
to a file.
.NXR "link" "defined" 
A file, together with
its size and all its protection
information may have several links to it.
There are two kinds of links: hard links and symbolic links.
.PP
By default
.PN ln
makes hard links.
A hard link to a file is indistinguishable from the
original directory entry. 
.NXR "hard link" "defined"
Any changes to a file are effective independent of the name used
to reference the file.
Hard links may not span file systems and may not refer to directories.
.PP
Given one or two arguments,
.PN ln
creates a link to an existing file
.IR name1 .
If
.I name2
is given, the link has that name.
The
.I name2
may also be a directory in which to place the link.
Otherwise it is placed in the current directory.
If only the directory is specified, the link is made
to the last component of
.IR name1 .
.PP
Given more than two arguments,
.PN ln
makes links to all the named files in the named directory.
The links made have the same name as the files being linked to.
.SH Options
.NXR "ln command" "options"
.IP \fB\-f\fR 5 
Forces existing
.I destination
pathnames to be removed before linking 
without prompting for confirmation.
.IP \fB\-i\fR 5
Write a prompt to standard output requesting information for each link
that would overwrite an existing file. If the 
response from standard input is
affirmative, and if permissions allow, the link is done. The 
.B \-i 
option has
this effect even if the standard input is not a terminal.
.IP \fB\-s\fR 5
Creates a symbolic link.
.IP
A symbolic link contains the name of the file to
which it is linked.  
.NXR "symbolic link"
The referenced file is used when an 
.MS open 2
operation is performed on the link.
A 
.MS stat 2
on a symbolic link returns the linked-to file. 
An 
.MS lstat 2 
must be done to obtain information about the link.
The 
.MS readlink 2
call may be used to read the contents of a symbolic link.
Symbolic links may span file systems and may refer to directories.
.SH See Also
cp(1), mv(1), rm(1), link(2), readlink(2), stat(2), symlink(2)