debian/manpages/exim_lock.8

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   5 .TH EXIM_LOCK 8 "March 26, 2003"
   6 .\" Please adjust this date whenever revising the manpage.
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  20 .SH NAME
  21 exim_lock \- Mailbox maintenance
  22 .SH SYNOPSIS
  23 .B exim_lock
  24 .RI [ options ] mailbox-file
  25
  26 .SH DESCRIPTION
  27 The
  28 .B exim_lock
  29 utility locks a mailbox file using the same algorithm as Exim.
  30 For a discussion of locking issues, see section 25.2.
  31 .B exim_lock
  32 can be used to prevent any modification of a mailbox by Exim or a user
  33 agent while investigating a problem.
  34 The utility requires the name of the file as its first argument.
  35 If the locking is successful, the second argument is run as a command
  36 (using C's \(lqsystem()\(rq function); if there is no second argument, the value
  37 of the SHELL environment variable is used; if this is unset or empty,
  38 /bin/sh is run.
  39 When the command finishes, the mailbox is unlocked and the utility ends.
  40 The following options are available:
  41 .TP
  42 .I \-fcntl
  43 Use \(lqfcntl()\(rq locking on the open mailbox.
  44 .TP
  45 .I \-interval
  46 This must be followed by a number, which is a number of seconds; it
  47 sets the interval to sleep between retries (default 3).
  48 .TP
  49 .I \-lockfile
  50 Create a lock file before opening the mailbox.
  51 .TP
  52 .I \-mbx
  53 Lock the mailbox using MBX rules.
  54 .TP
  55 .I \-q
  56 Suppress verification output.
  57 .TP
  58 .I \-retries
  59 This must be followed by a number; it sets the number of times to try
  60 to get the lock (default 10).
  61 .TP
  62 .I \-timeout
  63 This must be followed by a number, which is a number of seconds; it
  64 sets a timeout to be used with a blocking \(lqfcntl()\(rq lock.
  65 If it is not set (the default), a non-blocking call is used.
  66 .TP
  67 .I \-v
  68 Generate verbose output.
  69
  70 If none of
  71 .I \-fcntl, \-lockfile
  72 or
  73 .I \-mbx
  74 are given, the default is to create a lock file and also use \(lqfcntl()\(rq locking
  75 on the mailbox, which is the same as
  76 .B Exim's
  77 default.
  78 The use of
  79 .I \-fcntl
  80 requires that the file be writable; the use
  81 of
  82 .I \-lockfile
  83 requires that the directory containing the file be writable.
  84 Locking by lock file does not last for ever; Exim assumes that a lock file
  85 is expired if it is more than 30 minutes old.
  86
  87 The
  88 .I \-mbx
  89 option is mutually exclusive with
  90 .I \-fcntl.
  91 It causes a shared lock to be taken out on the open mailbox, and an
  92 exclusive lock on the file /tmp/.n.m where n and m are the device number
  93 and inode number of the mailbox file.
  94 When the locking is released, if an exclusive lock can be obtained for the
  95 mailbox, the file in /tmp is deleted.
  96
  97 The default output contains verification of the locking that takes place.
  98 The
  99 .I \-v
 100 option causes some additional information to be given.
 101 The
 102 .I \-q
 103 option suppresses all output except error messages.
 104 .PP
 105 A command such as
 106
 107   exim_lock /var/spool/mail/spqr
 108
 109 runs an interactive shell while the file is locked, whereas
 110
 111   exim_lock \-q /var/spool/mail/spqr <<End
 112   <some commands>
 113   End
 114
 115 runs a specific non-interactive sequence of commands while the file is
 116 locked, suppressing all verification output.
 117 A single command can be run by a command such as
 118
 119   exim_lock \-q /var/spool/mail/spqr \
 120     "cp /var/spool/mail/spqr /some/where"
 121
 122 Note that if a command is supplied, it must be entirely contained within
 123 the second argument - hence the quotes.
 124
 125 .SH BUGS
 126 This manual page needs a major re-work. If somebody knows better groff
 127 than us and has more experience in writing manual pages, any patches
 128 would be greatly appreciated.
 129
 130 .SH SEE ALSO
 131 .BR exim (8),
 132 /usr/share/doc/exim4\-base/
 133
 134 .SH AUTHOR
 135 This manual page was stitched together from spec.txt by
 136 Andreas Metzler <ametzler at downhill.at.eu.org>,
 137 for the Debian GNU/Linux system (but may be used by others).