Codex

dotlock

Section: User Manuals (1)

Updated: AUGUST 1999

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NAME

mutt_dotlock - Lock mail spool files.

SYNOPSIS

mutt_dotlock [-t|-f|-u|-d] [-p] [-r retries] file

DESCRIPTION

mutt_dotlock implements the traditional mail spool file locking method: To lock file, a file named file.lock is created. The program operates with group mail privileges if necessary.

OPTIONS

-t
Just try. mutt_dotlock won't actually lock a file, but inform the invoking process if it's at all possible to lock file.:
-f
Force the lock. If another process holds a lock on file longer than a certain amount of time, mutt_dotlock will break that lock by removing the lockfile.:
-u
Unlock. mutt_dotlock will remove file.lock.:
-d
Delete. mutt_dotlock will lock file, remove it if it has length 0, and afterwards remove file.lock.:
-p
Use privileges. If given this option, mutt_dotlock will operate with group mail privileges when creating and deleting lock files.:
-r retries
This command line option tells mutt_dotlock to try locking retries times before giving up or (if invoked with the -f command line option) break a lock. The default value is 5. mutt_dotlock waits one second between successive locking attempts.:

FILES

file.lock
The lock file mutt_dotlock generates.:

SEE ALSO

fcntl?(2), flock?(2), lockfile?(1), mutt?(1)

DIAGNOSTICS

mutt_dotlock gives all diagnostics in its return values:

0 - DL_EX_OK
The program was successful.:
1 - DL_EX_ERROR
An unspecified error such as bad command line parameters, lack of system memory and the like has occurred.:
3 - DL_EX_EXIST
The user wants to lock a file which has been locked by another process already. If mutt_dotlock is invoked with the -f command line option, mutt_dotlock won't generate this error, but break other processes' locks.:
4 - DL_EX_NEED_RPIVS
This return value only occurs if mutt_dotlock has been invoked with the -t command line option. It means that mutt_dotlock will have to use its group mail privileges to lock file.:
5 - DL_EX_IMPOSSIBLE
This return value only occurs if mutt_dotlock has been invoked with the -t command line option. It means that mutt_dotlock is unable to lock file even with group mail privileges.:

NOTES

mutt_dotlock tries to implement an NFS-safe dotlocking method which was borrowed from lockfile (1).

If the user can't open file for reading with his normal privileges, mutt_dotlock will return the DL_EX_ERROR exit value to avoid certain attacks against other users' spool files. The code carefully avoids race conditions when checking permissions; for details of all this see the comments in dotlock.c.

HISTORY

mutt_dotlock is part of the Mutt mail user agent package. It has been created to avoid running mutt with group mail privileges.

AUTHOR

Thomas Roessler <[email protected]>


Index

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

FILES

SEE ALSO

DIAGNOSTICS

NOTES

HISTORY

AUTHOR


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