04-11-2005
This depends on a lot things. If the processes both opened the file in append mode and really are doing write's, it should work ok. Multiple processes can all write to a common log file this way. Without append mode, they may step on each other. Your thread title mentions file locking. If the processes are using file locking correctly they cannot simultaneously write. If a process has a manditory lock on a file region, another non-root process will block if it attempts a write on that region. Advisory locks can be ignored. "man lockf" should give you more info about file locking.
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LEARN ABOUT OSF1
proplist
proplist(4) Kernel Interfaces Manual proplist(4)
NAME
proplist - The storing, parsing, and retrieving of Extended File Attributes
DESCRIPTION
Tru64 UNIX supports the storing, parsing, and retrieving of Extended File Attributes. An Extended File Attribute is a name and value pair
that is contained in a variable-sized structure called a Property List. A Property List is part of a file's metadata and can contain
abstract name and value pairs (Extended File Attributes) that can be set either by the operating system (for example, ACLs and privileges)
or by a user-level application (for example, PC File Attributes).
Since Extended File Attributes are treated as an extension to a file's metadata, they are synchronously updated, thereby ensuring consis-
tency. Note that Extended File Attributes set by user-level applications are treated as opaque and can be virtually anything.
To ensure that all Property List names are unique, you must register your Property List names with Compaq. Those Property List names with
a prefix are reserved by Compaq. In the case of conflicts, Compaq reserves the right to arbitrate the naming conventions of Property
Lists.
To register a Property List name, send a request by network mail to or write to:
Tru64 UNIX File System Group
ATTN: Property List Administrator
Compaq Computer Corporation
110 Spit Brook Road
Nashua, NH. 03062-2698
M/S ZKO3-3/U14
Several user-level routines, listed in the Related Information section, work together to manipulate Extended File Attributes. For example:
To set attributes, you use the sizeof_proplist_entry(3) and add_proplist_entry(3) routines to initialize the Extended File Attribute buffer
passed to setproplist(3) or fsetproplist(3). To fetch attributes, you use getproplist(3) or fgetproplist(3). To parse the attribute buf-
fer returned by setproplist(3) or fsetproplist(3), use the get_proplist_entry(3) routine.
The format of the Extended File Attributes buffer, the values of the system-wide properties, and the format of the Property List structures
are all defined in sys/proplist.h.
NOTES
Extended File Attributes are supported by the Advanced File System (AdvFS), the UNIX File System (UFS), and the Network File System (NFS).
The latter through the use of the proplistd daemon and the mount -o proplist command.
The archive utilities and support files with Extended File Attributes. However, third-party archive utilities may not support Extended
File Attributes and, consequently, if they are used on files with Extended File Attributes, the Extended File Attributes will be lost.
RELATED INFORMATION
Functions: add_proplist_entry(3), delproplist(3), fdelproplist(3), fgetproplist(3), fsetproplist(3), get_proplist_entry(3), getproplist(3),
setproplist(3), sizeof_proplist_entry(3).
Files: libproplist.a, libproplist.so, sys/proplist.h, acl(4).
Daemons: proplistd(8). delim off
proplist(4)