bause@exunido.uucp (Falko Bause) (07/28/89)
I want to allow only mutually exclusive write-accesses to a certain file. I've searched through the manual pages and have only found commands like lockf. But these commands only allow to establish a mutual exlusive access for sub-processes of some process. Let's explain, what I want, through an example: There is a file (e.g.) named text. I want that the following commands getting only exclusive write access: du > text ls -R > text myprog > text etc. I think that this a basic problem and therefore UNIX should have some buildins. E.g. VAX/VMS and Apollo/Aegis support setting some file attributes and mutual exclusion is performed by the operating system. But chmod, I think, doesn't has this possibility. Is there an easy way to perform mutual exclusion? Thanks in advance Falko
abcscnge@csuna.csun.edu (Scott "The Pseudo-Hacker" Neugroschl) (07/31/89)
In article <1505@laura.UUCP> bause@exunido.UUCP (Falko Bause) writes:
]
]I want to allow only mutually exclusive write-accesses to a certain file.
]I've searched through the manual pages and have only found commands
]like lockf. But these commands only allow to establish a mutual
]exlusive access for sub-processes of some process.
]
]Let's explain, what I want, through an example:
]
]There is a file (e.g.) named text. I want that the following commands
]getting only exclusive write access:
] du > text
] ls -R > text
] myprog > text etc.
]
This is kind of kludgy, but how about:
( chmod 600 text ; du ) > text
This allows "text" to be writable only by you. If you don't want yourself
to overwrite your own data:
( chmod 400 text ; du ) > text
or, if you're REALLY paranoid:
( chmod 000 text ; du ) > text
The shell creates "text" before executing the subshell commands, thus
the file is ALREADY open, so there is no problem with changing the modes.
Of course, the last is kind of useless, cuz you have to chmod text to some
readable mode.
--
Scott "The Pseudo-Hacker" Neugroschl
UUCP: ...!sm.unisys.com!csun!csuna.csun.edu!abcscnge
-- Beat me, Whip me, make me code in Ada
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