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dotlock(1) User Manuals dotlock(1) NAME lbdb_dotlock - Lock mail spool files. SYNOPSIS lbdb_dotlock [-t|-f|-u|-d] [-r retries] file DESCRIPTION dotlock implements the traditional mail spool file locking method: To lock file, a file named file.lock is created. OPTIONS -t Just try. dotlock won't actually lock a file, but inform the invok- ing 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, dotlock will break that lock by removing the lockfile. -u Unlock. dotlock will remove file.lock. -d Delete. dotlock will lock file, remove it if it has length 0, and afterwards remove file.lock. -r retries This command line option tells 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. dotlock waits one second be- tween successive locking attempts. FILES file.lock The lock file dotlock generates. SEE ALSO fcntl(2), flock(2), lockfile(1), lbdb-fetchaddr(1) DIAGNOSTICS 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 dotlock is invoked with the -f command line op- tion, dotlock won't generate this error, but break other processes' locks. 4 - DL_EX_NEED_RPIVS This return value only occurs if dotlock has been invoked with the -t command line option. It means that dotlock will have to use its group mail privileges to lock file. 5 - DL_EX_IMPOSSIBLE This return value only occurs if dotlock has been invoked with the -t command line option. It means that dotlock is unable to lock file. NOTES 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, 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 dot- lock.c. HISTORY 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 <roessler@guug.de> Unix JANUARY 2016 dotlock(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FILES | SEE ALSO | DIAGNOSTICS | NOTES | HISTORY | AUTHOR
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