02-08-2008
File read/delete synchronization in unix
Hi,
I have 2 processes that will be accessing the same file. First process first reads from the file, closes it and then opens it again to write to it (this is done sequentially). The second process may delete the file on some condition. These processes are independent of each other now.
What I'd like to know is whether unix handles the delete synchronously i.e. if the file is being read and the first process is holding on to the file handler, will the second process fail deletion, or will the deletion succeed but the read will fail. Similarly when the first process is doing the write.
As of now we wouldn't like to introduce any special synchronization between these two processes if the behavior is known. Please let me know where I can find more details about this.
Thanks.
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LEARN ABOUT SUSE
ansi_ctrlu
term::ansi::ctrl::unix(n) Terminal control term::ansi::ctrl::unix(n)
__________________________________________________________________________________________________________________________________________________
NAME
term::ansi::ctrl::unix - Control operations and queries
SYNOPSIS
package require Tcl 8.4
package require term::ansi::ctrl::unix ?0.1?
::term::ansi::ctrl::unix::import ?ns? ?arg...?
::term::ansi::ctrl::unix::raw
::term::ansi::ctrl::unix::raw
::term::ansi::ctrl::unix::columns
::term::ansi::ctrl::unix::rows
_________________________________________________________________
DESCRIPTION
WARNING: This package is unix-specific and depends on the availability of two unix system commands for terminal control, i.e. stty and
tput, both of which have to be found in the $PATH. If any of these two commands is missing the loading of the package will fail.
The package provides commands to switch the standard input of the current process between raw and cooked input modes, and to query the size
of terminals, i.e. the available number of columns and lines.
API
INTROSPECTION
::term::ansi::ctrl::unix::import ?ns? ?arg...?
This command imports some or all attribute commands into the namespace ns. This is by default the namespace ctrl. Note that this is
relative namespace name, placing the imported command into a child of the current namespace. By default all commands are imported,
this can howver be restricted by listing the names of the wanted commands after the namespace argument.
OPERATIONS
::term::ansi::ctrl::unix::raw
This command switches the standard input of the current process to raw input mode. This means that from then on all characters typed
by the user are immediately reported to the application instead of waiting in the OS buffer until the Enter/Return key is received.
::term::ansi::ctrl::unix::raw
This command switches the standard input of the current process to cooked input mode. This means that from then on all characters
typed by the user are kept in OS buffers for editing until the Enter/Return key is received.
::term::ansi::ctrl::unix::columns
This command queries the terminal connected to the standard input for the number of columns available for display.
::term::ansi::ctrl::unix::rows
This command queries the terminal connected to the standard input for the number of rows (aka lines) available for display.
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category term of
the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
KEYWORDS
ansi, columns, control, cooked, input mode, lines, raw, rows, terminal
COPYRIGHT
Copyright (c) 2006 Andreas Kupries <andreas_kupries@users.sourceforge.net>
term 0.1 term::ansi::ctrl::unix(n)