dotlock

NAME

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 occured.

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

Index

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

FILES

SEE ALSO

DIAGNOSTICS

NOTES

HISTORY

AUTHOR