command_options.txt

操作系统文件管理

							1999-05-31
							Emil Brink

			Command Options

1. INTRODUCTION
As of version 0.11.4, gentoo includes user interface controls for
a number of "command options". These options allow you some control
over how some of the built-in commands perform their actions, thus
allowing you to further customize gentoo's behaviour.


2. COMMAND OPTION DESCRIPTIONS
The command options are presented in the main configuration window,
on the page labeled "Command Options".
	The options are organized on one page per command, with
a row of tabs allowing you to choose which command to customize.
The interface is automatically generated, which is why it currently
might look a little less slick than other parts of the GUI (at least
to me, it does).
	The descriptions here are arranged with one section per
option page, ordered alphabetically (as are the pages in the actual
interface).

2.1 Copy
The Copy command has the following options:

Preserve Dates During Copy?
	When set, this boolean option will cause the Copy command to
	attempt to also copy the access and modification dates of the
	original file. This is done using the utime(2) system call.

Leave Failed Destination if Full Size?
	Normally, the Copy command will remove the destination file if
	an error occurs during the copying operation. This option,
	however, will (when set) cause the Copy command to leave the
	destination file, if it has the same size as the source file.
		This is sometimes useful in combination with the above
	option, since the date setting might fail on some file systems.

Buffer Size
	This lets you set the number of bytes gentoo reads and writes
	while copying. Setting it to a large value might increase per-
	formance (since fewer system calls are being done, and more
	bytes transferred per call), while setting it lower will help
	conserve memory.
		The default setting is 256 KB, which seems to give
	reasonable performance.

2.2 DpFocus
The DpFocus has just a single option:

Wrap Around at Top and Bottom?
	When set, this option will cause the focus bar, when moved by
	"DpFocus prev/next" commands, to wrap around when you try to
	move it out of the pane. This means that if you're on the top
	row of a pane, and run "DpFocus prev", you will move to the
	last row. If, on the other hand, the option was not set, then
	the commandw would have no effect.


2.3 GetSize
The GetSize command has only a single option:

Unselect Rows When Done?
	When set, this option causes the GetSize command to unselect
	each (directory) row, after it has computed the size for it.
	This is the default behaviour, and is consistent with the
	way all other commands in gentoo work.
		When not set, rows will be left selected. This is
	somtimes useful, e.g. when issuing a GetSize command in order
	to determine if for example a Copy will succeed. In these
	cases it is nice not having to re-select the rows after the
	sizes has been computed.


2.4 Information
The Information command has the following options:

Recurse Directories?
	When set, this option will cause the Information command to
	"dive" into selected directories, and recursively compute the
	size of the contents. When set, an extra row (with the label
	"Contents") will appear in the Information window for each
	directory.

Access, Modify and Change Date Formats
	These three strings allow you to specify the how the command
	shall format the dates it display. There are three dates per
	file, hence the three formatting strings.
		For information about the syntax for these format
	strings, see the strftime(3) manual page.
		The default format used is "%Y-%m-%d %H:%M.%S",
	which cause the date to appear in the ISO standard format of
	YYYY-MM-DD, followed by the time in 24-hour notation.


2.5 MkDir
The MkDir command has only one option:

CD Into New Directory?
	This boolean, when set, will cause the MkDir command to enter
	the freshly created directory. This option is also available
	in the actual MkDir window, for convenience.


2.6 ViewText
The ViewText command, and its relatives the ViewHex and ViewTextOrHex
commands, have the following options in common (not all are used by
all commands):

Use mmap() To Speed Loading?
	This option causes the ViewText command to issue a mmap()
	system call on the file being viewed. This gives very good
	performance, both in file viewing and the GTK+ display of
	the loaded text. The downside is that it might use up a lot
	of memory, and possibly fail on large files.
		ViewText will only mmap() files that have a size
	larger than 0. 0-length files will be opened and read seq-
	uentially. This is mainly useful for the special files found
	in the /proc filesystem on Linux, since they have 0 length.

Buffer Size
	This lets you set the size of the read buffer used by the
	ViewText command when mmap() (see above) is NOT being used.
		As usual, a large buffer might improve performance,
	while a small conserves memory.

Hex-Check First
	This option lets you set the number of bytes read (from the
	start of a file) by the ViewTextOrHex command when it is
	trying to determine how to view the file.
		A larger value will improve the accuracy of the
	decision, but take more time.
		The default value is 512 bytes.