xenial (1) mutt_dotlock.1.gz

Provided by: mutt_1.5.24-1ubuntu0.6_amd64 bug

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 <roessler@does-not-exist.org>