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Full Discussion: Speed problems with tar'ing a 500Gb directory on an eSATA drive
Top Forums UNIX for Advanced & Expert Users Speed problems with tar'ing a 500Gb directory on an eSATA drive Post 302624639 by Corona688 on Monday 16th of April 2012 01:28:20 PM
Old 04-16-2012
The hyphen has nothing to do with that. Neither does the dot, really. tar is simply recursive by design. Give it one folder and it'll archive all the contents. I don't think you can even turn that off.

There literally is a folder named dot no matter where you are. It's just short form for "current folder" and will work with any program that uses folders. Try ls . There's also a .. which means "one folder up from the current folder". These folder shortcut things are an extremely old feature and found nearly everywhere.

The hyphen tells tar to write to standard output instead of to an actual file. It'd spew it straight to the terminal if you didn't redirect it. But since you put a pipe after it, it puts it straight into rsh.

On the other end, where you extract with tar, the same - is taken to mean "read from standard input". And what is standard input? If you didn't pipe anything into it, it'd be reading straight from your terminal, but because of the pipe, it's reading from the program before -- tar.

So in this manner you create a tarball, feed it over the network, and extract it on the other end.
Last edited by Corona688; 04-16-2012 at 02:35 PM..
 

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LEARN ABOUT V7

rmf

RMF(1)								     [nmh-1.5]								    RMF(1)

NAME

       rmf - remove an nmh folder

SYNOPSIS

       rmf [+folder] [-interactive | -nointeractive] [-version] [-help]

DESCRIPTION

       Rmf removes all of the messages (files) within the specified (or default) folder, and then removes the folder (directory) itself.

       If  there  are  any  files  within the folder which are not a part of nmh, they will not be removed, and an error will be produced.  If the
       folder is given explicitly or the -nointeractive option is given, then the folder will be removed  without  confirmation.   Otherwise,  the
       user  will be asked for confirmation.  If rmf can't find the current folder, for some reason, the folder to be removed defaults to `+inbox'
       (unless overridden by user's profile entry "Inbox") with confirmation.

       If the folder being removed is a subfolder, the parent folder will become the new current folder, and rmf will produce  a  message  telling
       the user this has happened.  This provides an easy mechanism for selecting a set of messages, operating on the list, then removing the list
       and returning to the current folder from which the list was extracted.

       If rmf s used on a read-only folder, it will delete all the (private) sequences (i.e., "atr-seq-folder" entries) for this folder from  your
       context without affecting the folder itself.

       Rmf irreversibly deletes messages that don't have other links, so use it with caution.

FILES

       $HOME/.mh_profile	  The user profile

PROFILE COMPONENTS

       Path:		    To determine the user's nmh directory
       Current-Folder:	    To find the default current folder
       Inbox:		    To find the default inbox

SEE ALSO

       rmm(1)

DEFAULTS

       `+folder' defaults to the current folder, usually with confirmation
       `-interactive' if +folder' not given, `-nointeractive' otherwise

CONTEXT

       Rmf  will  set the current folder to the parent folder if a subfolder is removed; or if the current folder is removed, it will make "inbox"
       current.  Otherwise, it doesn't change the current folder or message.

BUGS

       Although intuitively one would suspect that rmf works recursively, it does not.	Hence if you have a sub-folder within a folder,  in  order
       to rmf the parent, you must first rmf each of the children.

MH.6.8								   11 June 2012 							    RMF(1)
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