mutt_dotlock(1) - man - phpMan

dotlock(1)                                  User Manuals                                  dotlock(1)



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 re‐
              move file.lock.

       -p     Use privileges.  If given this option, mutt_dotlock will operate with group mail priv‐
              ileges 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 lock‐‐
       file (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 run‐
       ning mutt with group mail privileges.

AUTHOR
       Thomas Roessler <roessler AT does-not-exist.org>



Unix                                         AUGUST 1999                                  dotlock(1)