Summery
シンボリックリンクを作成する。
※windowsでいうところのエイリアス
Construction
$ ln [option] [link] [symbolic-link]
Option
-s : シンボリックリンクを作成
-f : リンクファイルを警告無しに上書きをする
-n : ディレクトリを警告無しに上書きしてリンク作成をする
-v : リンク作成前にファイル名を表示
-i : リンクファイルがある場合に確認を行う
Sample
# /var/www階層をユーザーディレクトリにwebという名前でシンボリックリンクを作成する。
$ ln -s /ver/www ~/web
# 警告なしにシンボリックリンクを作る（更新などで上書きする時）
$ ln -sfn /ver/www ~/web
Coution
オプションの
-fと
-nは、取り返しのつかない事が発生する可能性があるので、慎重に行うこと。
データ消えます。
Discription
The ln utility creates a new directory entry (linked file) which has the same modes as
the original file. It is useful for maintaining multiple copies of a file in many
places at once without using up storage for the ``copies''; instead, a link ``points''
to the original copy. There are two types of links; hard links and symbolic links. How
a link ``points'' to a file is one of the differences between a hard and symbolic link.
The options are as follows:
-F If the target file already exists and is a directory, then remove it so that the
link may occur. The -F option should be used with either -f or -i options. If
none is specified, -f is implied. The -F option is a no-op unless -s option is
specified.
-h If the target_file or target_dir is a symbolic link, do not follow it. This is
most useful with the -f option, to replace a symlink which may point to a direc-
tory.
-f If the target file already exists, then unlink it so that the link may occur.
(The -f option overrides any previous -i options.)
-i Cause ln to write a prompt to standard error if the target file exists. If the
response from the standard input begins with the character `y' or `Y', then unlink
the target file so that the link may occur. Otherwise, do not attempt the link.
(The -i option overrides any previous -f options.)
-n Same as -h, for compatibility with other ln implementations.
-s Create a symbolic link.
-v Cause ln to be verbose, showing files as they are processed.
By default, ln makes hard links. A hard link to a file is indistinguishable from the
original directory entry; any changes to a file are effectively independent of the name
used to reference the file. Hard links may not normally refer to directories and may
not span file systems.
A symbolic link contains the name of the file to which it is linked. The referenced
file is used when an open(2) operation is performed on the link. A stat(2) on a sym-
bolic link will return the linked-to file; an lstat(2) must be done to obtain informa-
tion about the link. The readlink(2) call may be used to read the contents of a sym-
bolic link. Symbolic links may span file systems and may refer to directories.
Given one or two arguments, ln creates a link to an existing file source_file. If
target_file is given, the link has that name; target_file 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 will be made to the last component of source_file.
Given more than two arguments, ln makes links in target_dir to all the named source
files. The links made will have the same name as the files being linked to.
When the utility is called as link, exactly two arguments must be supplied, neither of
which may specify a directory. No options may be supplied in this simple mode of opera-
tion, which performs a link(2) operation using the two passed arguments.
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