SHELL命令之ln

root@bt:~/test# ln --helpUsage: ln [OPTION]... [-T] TARGET LINK_NAME   (1st form)  or:  ln [OPTION]... TARGET                  (2nd form)  or:  ln [OPTION]... TARGET... DIRECTORY     (3rd form)  or:  ln [OPTION]... -t DIRECTORY TARGET...  (4th form)In the 1st form, create a link to TARGET with the name LINK_NAME.In the 2nd form, create a link to TARGET in the current directory.In the 3rd and 4th forms, create links to each TARGET in DIRECTORY.Create hard links by default, symbolic links with --symbolic.When creating hard links, each TARGET must exist.  Symbolic linkscan hold arbitrary text; if later resolved, a relative link isinterpreted in relation to its parent directory.Mandatory arguments to long options are mandatory for short options too.      --backup[=CONTROL]      make a backup of each existing destination file  -b                          like --backup but does not accept an argument  -d, -F, --directory         allow the superuser to attempt to hard link                                directories (note: will probably fail due to                                system restrictions, even for the superuser)  -f, --force                 remove existing destination files  -n, --no-dereference        treat destination that is a symlink to a                                directory as if it were a normal file  -i, --interactive           prompt whether to remove destinations  -s, --symbolic              make symbolic links instead of hard links  -S, --suffix=SUFFIX         override the usual backup suffix  -t, --target-directory=DIRECTORY  specify the DIRECTORY in which to create                                the links  -T, --no-target-directory   treat LINK_NAME as a normal file  -v, --verbose               print name of each linked file      --help     display this help and exit      --version  output version information and exitThe backup suffix is `~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.The version control method may be selected via the --backup option or throughthe VERSION_CONTROL environment variable.  Here are the values:  none, off       never make backups (even if --backup is given)  numbered, t     make numbered backups  existing, nil   numbered if numbered backups exist, simple otherwise  simple, never   always make simple backups